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By Travis Yule — CEO & Founder, Full Send Funding
A profitable business runs out of cash above one growth rate — retained margin ÷ working-capital intensity, 16.0% a year for a 6% business with a 73-day cycle.
In one sentence: A profitable business runs out of cash above one calculable growth rate — retained margin divided by working-capital intensity — because growth raises the working capital the cash conversion cycle holds in proportion to revenue, while profit refills it in proportion to margin.
Profitable companies run out of cash because revenue arrives after the cash it takes to earn it, and growth widens that gap faster than profit fills it. A business that sells more this month than last pays for the extra labour, materials and inventory now and collects for them later. The working capital that bridges the two goes out first, and it goes out in proportion to the growth. Profit refills the bridge — but profit is a percentage of revenue, working capital is a multiple of the collection cycle, and above a specific growth rate the second outruns the first. That rate can be calculated from three numbers most owners already have: net margin, the cash conversion cycle, and the share of profit left in the business. This article calculates it.
The usual framing gets the diagnosis backwards. When cash tightens in a growing business the instinct is to look for the leak — a customer paying slowly, a bad month, a cost that crept. Sometimes one of those is there. More often nothing is wrong at all. The company is doing exactly what it planned, every job is profitable, and the balance is falling because the plan requires more working capital than the plan generates. Robert Higgins gave that limit a name in 1977: the sustainable growth rate, the fastest a firm can grow without raising new equity or changing how it is financed.[1] The corporate version is taught in every finance course. The small-firm version, which drops the balance sheet a $2 million company does not really have and keeps the arithmetic, is what follows.
Two things make it worth working out rather than sensing. The first is that the number is usually lower than owners expect: for a business at a 6% net margin with a 73-day cycle, whose owner draws half the profit, it is 16.0% a year, and the same business growing 40% is short about $108,000 by the end of the year with nothing having gone wrong. The second is that the levers that raise it cost less than the capital that replaces it, and the financing that fits the gap has a specific shape — three shapes, in fact, and one widely sold product that does not fit at all.
Every unit of work a business does follows the same sequence. Money leaves to pay for labour, materials or stock. The work sits as inventory or work in progress for some number of days. It is delivered and invoiced. The customer pays some number of days after that. The distance from the first step to the last, less the days your own suppliers let you wait, is the cash conversion cycle: days inventory outstanding plus days sales outstanding minus days payables outstanding. A fuller treatment of the cycle and how to measure yours is in the operator's guide to the cash conversion cycle and in what working capital is and how much to keep; the point here is what it does under growth.
Across a whole year the cycle sets a standing requirement. If the business spends a certain amount every day and each day's spending comes back after the cycle's length, the amount permanently out of the account at any moment is close to the daily operating outflow multiplied by the cycle in days. For a business with $2,400,000 of annual revenue, a 6% net margin and a 73-day cycle, the daily outflow is $2,256,000 ÷ 365, or $6,180.82, and the requirement is $6,180.82 × 73 = $451,200. That money is not lost. It is in receivables, in inventory and in work nobody has invoiced yet, and it comes back — replaced immediately by the next cycle's outflow. It is the price of admission to operating at that volume, and the SBA's own guidance to owners puts the cash-flow projection at the centre of planning for exactly this reason: it is the instrument that shows how much working capital the business will need before it needs it.[6]
Three consequences follow, and the third is the one this article is about.
The requirement does not depend on profitability. A 6% business and a 2% business with the same revenue and the same cycle need almost the same working capital. Profit decides whether the business can build that capital over time; it does not reduce the amount.
The requirement scales with revenue. Double the volume and the daily outflow doubles, so the amount permanently out of the account doubles. This is a multiplication, not a rule of thumb, and it holds whether the growth is one large contract or a hundred small ones.
The increase has to be funded before the growth pays for it. The extra working capital goes out during the months the business is growing, from a balance sized for last year's volume. The profit on the new revenue arrives at the end of the cycle, and only a share of it stays in the business. Whether that share is enough is a comparison between two numbers, and it can be made exactly.
Higgins’s original formula was written for a corporation with a balance sheet: the sustainable growth rate is the return on equity multiplied by the share of earnings retained, on the assumption that the firm keeps its debt-to-equity ratio constant and raises no new shares.[1] A small private business does not think in those terms, but the logic transfers cleanly if one substitution is made. The capital the business actually has to grow is its working capital — the standing requirement above — and the return on that capital is the net profit divided by it.
Write the annual revenue as R, the net margin as m (after tax, before the owner's draw), the cash conversion cycle in days as CCC, and the share of net profit left in the business rather than drawn as b. Then:
Growth is self-funding as long as retained profit covers the increase, and the rate at which the two are exactly equal is the sustainable growth rate:
Sustainable growth rate = (b × m × 365) ÷ ((1 − m) × CCC)
Read as words: retained margin divided by working-capital intensity. Revenue cancels out, which is why the rate is a property of the business model rather than its size — a $500,000 company and a $5 million one with the same margin, cycle and draw policy hit the same wall at the same growth rate. The table applies the formula across the margins and cycles we see most often on the statements of the businesses we fund.
The formula stated in the text, with the retained share at 1.0 in the first block and 0.5 in the second, and profit measured on the year the business grows from. Working capital is the only capital counted; equipment and any required cash floor lower every rate shown.
Two readings matter more than the rest. Down each column, the rate falls with margin more slowly than it falls with the cycle across each row: a 3% business with a 30-day cycle can grow faster from its own profit than a 10% business with a 120-day cycle. The collection cycle is the dominant term. And the second block halves the first, because an owner who draws half the profit has halved the capital available to grow — which is not a criticism of the draw, only an accounting of it.
The formula measures profit on the year the business is growing from, not the year it is growing into, because the working capital goes out before the new revenue's profit arrives. The exact version, which credits the retained profit on the grown year's revenue, gives a somewhat higher rate — for the worked example below, 19.0% rather than 16.0%. We use the conservative form throughout: a business that plans to the exact rate has no margin for a late payer, and late payers are the normal condition.
One more limit is worth stating before using the number. The formula counts only the working capital the cycle consumes. If growth also needs a vehicle, a second shop or a minimum cash cushion the bank covenant requires, those come out of the same retained profit and the sustainable rate is lower still. Equipment has its own financing shape and is priced on the asset rather than the cycle; the cash floor simply reduces b.
Abstractions do not make payroll, so here is a whole year with the numbers attached.
A commercial HVAC service contractor bills $2,400,000 a year — $200,000 a month, which is squarely in the revenue band we fund most often. Net margin after tax is 6%, so the business earns $144,000, and the owner draws half of it. Customers are on net-30 terms and pay in 58 days on average. Parts and equipment sit for 30 days between delivery and installation. Suppliers are paid in 15 days, because the distributor offers a discount for it. The cycle is therefore 30 + 58 − 15 = 73 days.
The standing requirement. $2,400,000 × 0.94 × 73 ÷ 365 = $451,200 permanently out of the account. That is more than three years of the company's entire net profit, and it is the ordinary condition of the business, not a problem.
The sustainable growth rate. Retained profit is 0.5 × 6% × $2,400,000 = $72,000. Working-capital intensity is 0.188. So the business can fund $72,000 ÷ 0.188 = $382,979 of new revenue from its own profit — a growth rate of 16.0%. If the owner drew nothing, it would be 31.9%. Either way, it is a great deal less than the 40% the company is about to grow.
The year it wins the work. A property manager awards the company a maintenance portfolio worth $960,000 a year, on the same net-30 terms the rest of the book is on. Revenue goes to $3,360,000. The requirement goes to $3,360,000 × 0.188 = $631,680. The increase is $180,480, and it goes out over the months the new sites come on — technicians hired ahead of the first invoices, parts stocked, sixty days of new receivables building before the first payment lands. Against it the business has $72,000 of retained profit. The gap is $108,480. Crediting the profit on the new revenue as it is earned narrows the gap to $79,680; it does not close it.
The additional working capital a year of growth requires rises in a straight line with the growth rate and crosses the flat line of retained profit at 16%; every growth rate to the right of the crossing needs outside capital.
Working capital requirement = $2,400,000 × (1 − 0.06) × 73 ÷ 365 = $451,200; the additional requirement at each growth rate is that figure multiplied by the rate. Retained profit = 0.5 × 6% × $2,400,000 = $72,000, measured on the base year. The crossing is the sustainable growth rate, 16.0%.
The chart is the same arithmetic across every growth rate from standing still to 50%. The flat line is what the business generates; the rising line is what growth consumes; they cross at 16%. Everything to the right of the crossing has to come from somewhere other than profit, and the further right, the more of it.
What the gap looks like from inside the account. Nothing in this year involves a bad decision, and nobody sees a gap. What the owner sees is the month-end balance a little lower each month than the last while sales are the best they have ever been. The distributor's 15-day discount is the first thing to go, because paying at 30 days instead of 15 is the easiest working capital there is. The owner's draw is deferred a month, then two. Payroll is timed to the biggest receivable of the month. Somewhere around month eight the account touches zero on a Thursday, for the first time in the company's history, in the most profitable year it has ever had.
That is the sequence. It is worth recognising it as a sequence, because each step is sensible on its own, and each one is the business converting a source of working capital it had been holding in reserve into growth funding — supplier terms, the draw, the timing of payroll — until it runs out of sources.
The tell is specific: profit rising while cash falls, month after month. On a profit and loss statement the business looks better every quarter. On the bank statement the balance trends down and the deposits trend up, and the two lines are moving apart. A business with a genuine operating problem shows the opposite pair — deposits flat or falling with the balance — and the difference between the two is the first thing we look for when a growing business applies.
What underwriting reads from three months of statements is described from the decision side in how working capital underwriting actually works. Three of those signals behave in a particular way in a growth file, and it is worth knowing how before sending the statements.
The deposit trend is the case for the file. Deposits rising month over month is direct evidence that the revenue the capital is meant to bridge exists. It is a stronger fact than a signed contract, because it is already happening.
Average daily balance and negative days are read against that trend. A falling balance in a business whose deposits are rising reads as growth absorbing working capital, which is fundable. A falling balance in a business whose deposits are flat reads as a business spending more than it makes, which is not — borrowing adds a payment to it. The same balance figure means two different things, and the deposit trend is what decides which.
Sizing lags the growth. Funding size is derived from revenue at 80% to 150% of a month. But the statements are trailing: three months that average $200,000 produce a range of $160,000 to $300,000, while a business whose run-rate has reached $280,000 a month would be sized at $224,000 to $420,000 on its current volume. The difference is the growth itself. A growing business is therefore almost always a stronger file than its statements show, and the way to close the difference is to send what the statements cannot: the awarded contract, the receivables aging, the most recent month's deposits to date. Ask to be sized on the trend, and give the underwriter the evidence to do it.
Two things a growth file should not do. It should not arrive with a fresh advance already on the statements, because existing positions cause more declines than anything else and a position taken in a panic the month before is the worst kind. And it should not have let the negative days start. The moment to apply is when the balance has been falling for three months and is still positive, not the month after it first touched zero.
There is good survey evidence on how common the condition is and none at all on the specific mechanism, and a report should be clear about which is which.
The Federal Reserve Banks' Small Business Credit Survey is the broadest regular measurement of small-firm finances in the United States. In the 2026 report on employer firms, drawn from the 2025 survey, the most common reasons firms sought financing were to meet operating expenses, at 56%, and to pursue an expansion or new opportunity, at 46%.[2] The two are usually read as separate populations — struggling firms and growing ones. The arithmetic above says they overlap: a firm growing past its sustainable rate needs financing to meet operating expenses because it is pursuing an expansion. The survey does not ask the question that would separate them, so the size of the overlap is not known.
The prior year's report, on the 2024 survey, found that 51% of employer firms had experienced uneven cash flow as a financial challenge in the previous twelve months and 56% had experienced difficulty paying operating expenses.[3] These are self-reported categories from a nationwide convenience sample of employer firms with fewer than 500 employees; they measure prevalence, not cause, and nothing in them says how many of those firms were profitable at the time. We are not aware of any public dataset that does.
Survival data has the same shape. The SBA’s Office of Advocacy reports that over 1994 to 2022, an average of 67.7% of new employer establishments survived at least two years, and the five-year survival rate was 49.2%.[4] The Bureau of Labor Statistics' establishment data, which those figures are built from, shows that 34.7% of establishments opened in 2013 were still operating ten years later.[5] Neither series records why an establishment closed, and neither distinguishes a business that ran out of cash while profitable from one that never made money. The claim that most failures are cash-flow failures is repeated widely and is not, as far as we can find, measured anywhere. This article does not make it. What it makes is the narrower and provable claim that a profitable business growing above the rate in the table will run short of cash by an amount the formula gives, and that the shortfall is not evidence of anything being wrong.
Because the sustainable rate is a ratio, everything that changes it is one of four moves: shorten the cycle, widen the margin, keep more of the profit, or grow more slowly. Each has a cost and a size, and the size is calculable. The table applies each lever on its own to the worked example and then all of them together.
Each row applies the sustainable-growth formula to the inputs shown: base case $2,400,000 revenue, 6% net margin, 73-day cycle (30 days inventory + 58 days receivable − 15 days payable), half of profit retained. Revenue cancels out of the rate and is shown only for the dollar figures in the text.
Ranked by what is actually achievable in a quarter, from the files we see:
All four operating levers together take the example to 41.0%, which is above the growth it is about to attempt. That is the honest headline of the table: a 40% growth year can be self-funded by a business at these margins, but only by a business that runs every part of its cycle deliberately. Most do not, most cannot in the time available, and the difference is what financing is for.
Financing fills the gap between the sustainable rate and the actual one. The question is never only how much; it is what shape, because the requirement being funded has a shape — it is permanent while the volume lasts, it grows with revenue, and it is tied up in receivables and inventory the business can point to. Three structures match it.
A revolving line sized to what the cycle holds. A business line of credit drawn against receivables and inventory and repaid as they collect is the working-capital requirement financed in its own image: it rises when the cycle holds more and falls when it holds less, and it is priced on the drawn balance. It is also, precisely, Higgins's original assumption made real. His formula holds leverage constant, which means debt grows in proportion to the business; a line that scales with receivables is what that assumption looks like on a small firm's statements.[1] The effect on the sustainable rate is direct. If a line funds 40% of the working-capital requirement and grows with it, the owner's retained profit has to cover only the other 60% of each increase, and the example's rate rises from 16.0% to 26.6%. Lines here run from $10,000 to $2,000,000, and the trade-offs against a lump sum are set out in line of credit versus term loan.
A term facility sized to a step. When the growth is a discrete event — the portfolio award, a second location, a contract with a known start date — the increase in working capital is a known amount that goes out once and stays out. A working capital term facility sized to that increment, on a term long enough for the new revenue's profit to repay it, is the right shape: the example's $108,480 gap on a term of two to three years is serviced from the $57,600 a year the new revenue earns at a 6% margin, with room. The discipline is the one set out in when borrowing is the wrong answer — the money buys a specific thing, which returns a specific amount, by a specific date — and a growth step fills all three blanks better than almost any other use of capital. Terms here run from four months to three years; a term shorter than the cycle it is funding is the first sign the shape is wrong.
Funding attached to the receivable itself. Invoice factoring, purchase-order financing and revenue-based financing all scale with sales automatically, because the funding is a function of the invoice or the deposit rather than of a credit decision made last quarter. They cost more per dollar than a line, and they suit a business whose growth is faster than a facility can be resized, or whose receivables are stronger than its own credit — a subcontractor billing a rated general contractor, a manufacturer with a purchase order from a national buyer. Purchase-order financing covers when that trade is worth making.
The firm’s own classification. The shapes are described by what the funding scales with, because the requirement being funded scales with revenue and lasts as long as the volume does.
The one that does not fit. A short, fixed daily remittance sized against last year's deposits, taken to fund a permanent and growing requirement, and renewed or stacked each time the gap reopens. The product itself is not the problem; we sell short-term funding and say plainly what it is for. The mismatch is one of duration and direction. The requirement is permanent and rising; the advance is short and fixed. Its remittance is set against deposits that are being reinvested in the growth rather than accumulating, so the cash the remittance is paid from is exactly the cash the growth needs. And because the term is shorter than the life of the requirement, the gap is still there when the advance is paid off — reopened, larger, in a business whose balance now shows the remittance history. The second advance is priced on that history. The third is stacking, and the mechanism that follows is described there. A short advance fits a timing gap — a shortfall in which the revenue exists and arrives later than the expense — and a single growth step can be one. A standing requirement that grows every year is not.
On price: our cost of capital runs from 4.5% to 45% depending on qualifications and term, and the shape decides where in that range a growth file lands more than the amount does. The test is the same at any price. The example's $108,480 of growth capital funds $960,000 of new revenue that earns $57,600 a year; at a 20% annual cost the capital costs $21,696, and the growth clears it. At the top of the range on a short term it would not, which is a reason to fix the shape, not a reason to decline the growth.
The sustainable-growth arithmetic is a tool for one situation — a profitable business growing faster than its profit can fund — and it gives the wrong answer outside it. The cases below are where it should not be applied, and what to do instead.
The business is not profitable in a normal month. The formula's numerator is retained profit; if the margin is zero or negative the sustainable rate is zero or negative, and the honest reading is that there is no growth rate at which the business funds itself. That is a structural loss — a business that spends more than it makes in a normal month — and borrowing adds a payment to it, so the next shortfall is larger by exactly the new debt service. Growth into a loss makes the loss bigger faster. The answer is to find whether it is a pricing, cost or volume problem before funding anything.
The growth is not real yet. A pipeline is not revenue, and a requirement calculated on hoped-for volume funds inventory and payroll the business may not need. Fund the step when the contract is signed and the start date is known, and size to the contract rather than the forecast.
The operation cannot absorb the growth. If the constraint is supervisors, systems or a licence rather than cash, capital buys none of those quickly and the working capital it provides gets spent on a business that cannot yet deploy it. The formula assumes the business can do the work; check that first.
The requirement is a single customer's terms. If the whole gap traces to one account paying at 90 days on net-30, the problem is a customer, and the choice is between repricing that customer for the capital they are consuming, financing that receivable specifically, or declining the volume. General working capital for a specific customer's slow payment subsidises them at your cost.
Your actual growth is below the sustainable rate. Then the business is accumulating cash and does not need this article. The gap runs the other way, and the question is what to do with the surplus, which is a different and better problem.
The capital is for equipment or premises. Fixed assets are not part of the cycle and should not be funded from the working-capital facility that carries it. Equipment is priced against the asset's useful life, usually more cheaply, and taking it from the line leaves the cycle underfunded.
The number the formula gives is being used as a target. It is a ceiling, not a plan. A business growing at exactly its sustainable rate has no reserve for the one customer who pays in 90 days, and late payers are not an exception.
Profitable companies run out of cash because growth consumes working capital in proportion to revenue while profit refills it in proportion to margin, and above a specific rate the first outruns the second. That rate is retained margin divided by working-capital intensity — (share of profit retained × net margin × 365) ÷ ((1 − net margin) × cash conversion cycle in days) — and for a 6% business with a 73-day cycle whose owner draws half the profit it is 16.0% a year. Growing 40%, that business is $108,480 short by year-end with every job profitable. The tell is profit rising while cash falls; the levers, in order of what they move, are collecting faster, taking supplier terms, pricing, drawing less, and growing at the rate the business can carry; and the financing that fits is a revolving line that scales with the cycle, a term facility sized to a specific step, or funding attached to the receivable — never a short fixed remittance renewed against a requirement that is permanent and growing.
If you want the calculation run on your own numbers, the funding calculator sizes the capital side, or call 518-312-0382 with your margin, your collection days and the growth you are planning, and we will work the rest out with you.
Every number in the tables and the figure is derived from stated inputs, not surveyed. The sustainable-growth formula is Higgins’s 1977 result — retained earnings ratio times return on equity, with leverage held constant and no new equity[1] — restated for a firm whose only growth capital is its working capital: the requirement is annual revenue × (1 − net margin) × cash conversion cycle ÷ 365, the return on it is net profit ÷ requirement, and the growth rate at which retained profit equals the increase in the requirement is (retained share × net margin × 365) ÷ ((1 − net margin) × cycle days). Profit is measured on the year the business grows from; the alternative that credits the grown year’s profit is stated in the text where it differs. The grid applies the formula across net margins of 3%, 6% and 10%, cycles of 30 to 120 days and retained shares of 1.0 and 0.5; the worked example uses $2,400,000 of revenue, a 6% net margin, a 73-day cycle built from 30 days of inventory, 58 days of receivables and 15 days of payables, half of profit retained and a 40% growth year; the lever table changes one input at a time from that base and then all of them. The site’s arithmetic audit recomputes every published value from those inputs before publication.
The margins, cycles and retention shares are typical of the businesses the firm underwrites and are chosen to span what appears on their statements. They are not measured industry averages and none is claimed. The sizing range of 80% to 150% of monthly revenue, the line-of-credit range of $10,000 to $2,000,000, the term range of four months to three years and the cost-of-capital range are the firm’s published terms. The classification of financing shapes is the firm’s own.
The external figures are quoted as prevalence, not cause. The Federal Reserve Banks’ Small Business Credit Survey is a nationwide convenience sample of employer firms with fewer than 500 employees; the reasons-for-financing shares are from the 2026 report on the 2025 survey[2] and the financial-challenge shares from the 2025 report on the 2024 survey[3]. Survival rates are the SBA Office of Advocacy’s summary of Bureau of Labor Statistics establishment data for 1994 to 2022[4] and the BLS’s own figure for the 2013 cohort[5]. None of these sources records why a business closed or whether it was profitable when it did, and the article says so rather than inferring it.
Because the cash to do the work goes out before the revenue from it comes in, and the amount tied up in that gap rises in proportion to revenue. Growth raises the working capital requirement by the growth rate times the existing requirement; profit only refills it at the net margin times revenue. Above a specific growth rate the requirement rises faster than profit can fund it, and the balance falls while the profit and loss statement improves.
The fastest it can grow from retained profit alone. For a business whose capital is its working capital, it equals (share of profit retained × net margin × 365) divided by ((1 − net margin) × cash conversion cycle in days). A 6% margin, a 73-day cycle and half the profit retained give 16.0% a year. The formula measures profit on the year the business is growing from, which is the conservative version.
Multiply your annual revenue by (1 − net margin) and by your cash conversion cycle in days, then divide by 365. That is the working capital your current volume holds. Multiply it by the growth rate you plan: that is the additional cash the growth year consumes, most of it before the new revenue pays. Compare it with the profit you will leave in the business; the difference is what has to come from outside.
The collection cycle, in most files. On the worked example, collecting ten days faster raises the rate from 16.0% to 18.5% and fifteen more days of supplier terms raises it to 20.1%, before any change in price or in what the owner draws. Cycle days are worth more than margin points because the cycle sets the working-capital intensity that every dollar of growth is multiplied by.
One shaped like the requirement, which is permanent while the volume lasts and grows with revenue. A revolving line of credit sized to receivables and inventory scales with the cycle; a term facility sized to a specific step suits a discrete growth event on a term long enough for the new profit to repay it; factoring, purchase-order and revenue-based funding scale automatically with sales. Lines here run $10,000 to $2,000,000 and terms four months to three years.
Because the requirement is permanent and growing while the advance is short and fixed. Its remittance is paid from the same cash the growth needs, the term ends before the gap does, and each renewal is priced on the history the last one left. It fits a single timing gap with a known end; taken repeatedly against a standing requirement it becomes stacking.
The deposit trend against the balance trend. Deposits rising while the balance falls reads as growth absorbing working capital, which is fundable; deposits flat while the balance falls reads as a business spending more than it makes, which is not. Because sizing is derived from trailing revenue, a growing business should send the awarded contract, its receivables aging and the current month’s deposits so it can be sized on the trend rather than the average.
Sometimes. It is the only lever that closes the gap completely, and it is the right answer when the operation cannot absorb the growth, when the business is not profitable in a normal month, or when the gap traces to one customer’s slow payment. It is the wrong answer when the growth is real, profitable and within the operation’s capacity, because the return on the working capital then exceeds its cost by a wide margin.
Travis Yule founded Full Send Funding in 2021 and leads it from Middle Grove, New York. He writes about working capital from the underwriting side of the table — what the numbers actually have to say before a business gets funded.