The Cash Conversion Cycle: the Number That Explains Why You Are Out of Cash

Three numbers and one subtraction

Everything a trading business does with cash happens in a loop. You pay a supplier, the goods sit on a shelf, someone buys them, and eventually the customer pays you. The cash conversion cycle measures that loop in days. Days inventory outstanding is inventory divided by daily cost of sales — how long goods sit. Days sales outstanding is receivables divided by daily revenue — how long invoices sit. Days payable outstanding is payables divided by daily cost of sales — how long you sit on your own bills. Add the first two, subtract the third, and you have the number of days between paying for something and being paid for it.

The denominators are not the same, and that matters. Inventory and payables are carried at cost, so they are divided by cost of sales per day. Receivables carry a selling price, so they are divided by revenue per day. In the worked business — $7,300,000 of revenue, 60% cost of sales — revenue per day is $20,000 and cost of sales per day is $12,000. Divide $900,000 of inventory by $12,000 and you get 75 days. Divide $1,200,000 of receivables by $20,000 and you get 60. Divide $540,000 of payables by $12,000 and you get 45. Ninety days, all in.

Ninety days is a loan you are making to your own business

Days are the diagnostic; money is the consequence. Inventory plus receivables minus payables is $900,000 + $1,200,000 − $540,000 = $1,560,000. That is real money, permanently absent from the bank account for as long as the business trades at this size on these terms. It is 21.4% of annual revenue. Financed at 8%, it costs $124,800 a year in interest or forgone return — which on a 5% net margin is more than a third of the profit the business makes.

This is why the cycle is a better early-warning signal than the profit and loss account. Profit is an opinion about timing; the cycle is a measurement of it. A business can report a good year while its cycle stretches from 90 days to 110 because customers are paying late and stock is ageing, and the first visible symptom will be a bank balance that does not match the reported profit. Track the three components monthly, not annually — an annual figure computed from a year-end balance sheet is measured on the one day of the year when everybody tidies up.

Growth makes the hole bigger, and that is the counterintuitive part

Working capital is roughly proportional to sales. If the terms do not change, more revenue means more stock on the shelf and more invoices outstanding, and payables rise too but not enough to cover them. In the worked business, working capital is 21.4% of revenue. Grow revenue by 30% and working capital goes from $1,560,000 to $2,028,000 — an extra $468,000 that has to come from somewhere before a single new customer has paid. At a 5% net margin, the enlarged revenue produces $474,500 of profit. Growth just consumed 98.6% of it.

That coincidence is not a coincidence. Set the cash a percentage point of growth absorbs equal to the profit it generates and you get the growth rate a business can finance out of its own earnings: net margin divided by (working capital intensity minus net margin), or 0.05 ÷ (0.214 − 0.05) = 30.5%. Below that rate the business funds itself. Above it, every extra point of growth has to be paid for with a loan, an overdraft, an equity injection or a change in terms. Nothing in the profit and loss account tells you where that line is — the cycle does.

What one day is actually worth

There is a shortcut everyone uses — one day of cycle equals one day of revenue — and on this business it is wrong for two of the three levers. One day off days sales outstanding really is worth $20,000, because receivables are measured against revenue per day. But one day off days inventory outstanding, or one day added to days payable outstanding, is worth $12,000, because both are measured against cost of sales per day. The shortcut overstates the inventory and payables levers by a factor of 1.67. If you are ranking initiatives by cash released, that is enough to put them in the wrong order.

Put a realistic programme against all three and the arithmetic is easy. Take fifteen days out of inventory ($180,000), fifteen days out of collections ($300,000), and negotiate fifteen days more from suppliers ($180,000). The cycle halves from 90 days to 45, working capital falls from $1,560,000 to $900,000, and $660,000 of cash appears without a single extra sale. At an 8% cost of funds that is $52,800 a year, permanently. It is also a one-off cash inflow of $660,000, which is the part that matters if you are trying to fund the next stage of growth without borrowing.

When the cycle goes negative

Some businesses collect before they pay. A supermarket sells for cash and settles with suppliers in two months; a subscription platform bills annually in advance and pays its hosting monthly. Take the same $7,300,000 of revenue but with cost of sales at 75% — $15,000 a day — stock turning in 30 days, customers paying in 2, and suppliers paid in 60. Inventory is $450,000, receivables $40,000, payables $900,000. The cycle is 30 + 2 − 60 = −28 days, and working capital is −$410,000: the suppliers are funding $410,000 of the business, interest-free.

Now run the same 30% growth through it. Working capital moves from −$410,000 to −$533,000, so growth releases another $123,000 of cash instead of absorbing it. This is why a negative cycle is a structural advantage rather than a clever trick: it inverts the relationship between growth and funding. The faster the business grows, the more cash it produces before profit is even counted. It is also why it is difficult to copy. A negative cycle comes from the shape of the business model — selling for cash, buying on credit, holding little stock — and not from a payment-terms negotiation. Squeezing suppliers to manufacture one imports their financing cost into your purchase price, and often at a worse rate than a bank would charge.

Frequently asked questions

Should I divide receivables by revenue or by cost of sales?

By revenue. A receivable is an invoice at selling price, so the matching flow is revenue per day. Inventory and payables are both carried at cost, so they are matched against cost of sales per day. Mixing the denominators is the single most common error in a cash conversion cycle, and on the worked example it inflates the inventory and payables days by 67% each — which flatters the cycle by turning a 90-day figure into something closer to 60.

Why does a profitable, growing business run out of cash?

Because working capital scales with revenue. If the cycle absorbs 21.4% of revenue, then every extra $1,000,000 of sales locks up another $214,000 before any of it is collected, while the profit on that $1,000,000 at a 5% margin is only $50,000. The gap has to be financed. The break-even growth rate is net margin ÷ (working-capital intensity − net margin) — 30.5% in the worked example. Grow faster than that and you must borrow, raise equity, or shorten the cycle.

Is a negative cash conversion cycle always good?

Not automatically. It is genuinely advantageous when it comes from the business model — cash sales, low stock, ordinary supplier terms — because then growth funds itself. It is dangerous when it comes from paying suppliers late. Stretched payables are a liability that must eventually be settled, they usually cost more than bank debt once you count lost discounts and price increases, and in the EU they run into the late-payment rules. And a negative cycle magnifies a downturn: if sales fall, payables unwind faster than receivables come in.

How much cash does one day of the cycle release?

It depends which lever you pull. On $7,300,000 of revenue with 60% cost of sales, one day off days sales outstanding releases $20,000; one day off inventory or one day added to payables releases $12,000 each. Do not use a single blended number. If you want a quick planning figure, take revenue ÷ 365 for the collections lever and cost of sales ÷ 365 for the other two, and add the three amounts separately.

Which lever should I attack first?

Usually collections, for three reasons: each day is worth the most (it is measured against revenue, not cost), it costs nothing but process discipline, and it does not damage a relationship the way stretching a supplier does. Invoice on the day of delivery, make the terms explicit, chase before the due date rather than after, and put the largest overdue balances in front of a named person. Inventory comes second and is slower — it means better forecasting and slower-moving lines written down or delisted. Payables come last, because extending them transfers your problem to a supplier who will eventually price it back to you.