Cash conversion cycle: why DPO is subtracted
A question gives you three numbers: 40 days holding inventory, 30 days collecting from customers, 25 days before the company pays its suppliers. Add them and you get 95. It is the fastest arithmetic on the page and it is wrong, because the cash conversion cycle is not a total of every waiting period in the business. Those 25 supplier days are the one stretch where the company is holding its money instead of spending it.
Two cycles, one difference
The operating cycle tracks a unit of inventory from the day it arrives to the day the customer's payment clears. Nothing about suppliers enters it.
Operating cycle = DOH + DSO
The cash conversion cycle (CCC) asks a narrower question: how long is the company's own cash committed? Suppliers cover part of that stretch, so their days come out.
CCC = DOH + DSO − DPO
DOH is days of inventory on hand, DSO is days sales outstanding, DPO is days payables outstanding. Three similar labels, and under time pressure they blur into one pile of day counts. Two of them build the cycle. The third shortens it.
The minus sign is economics, not bookkeeping
DPO measures how long suppliers are willing to let the company owe them, which is a form of financing and a genuinely cheap one. For those 25 days the inventory sits on the shelves and the cash still sits in the bank. Stretch the payment terms and the company's money is tied up for fewer days, not more.
That is why adding DPO does more than flip a sign. It recasts a source of working capital as a drag on it, so the answer comes out not merely too big but backwards in meaning.
It also explains something that looks like an error when candidates first meet it. A negative CCC is normal for some businesses. Supermarkets take cash at the till and pay their suppliers weeks later, so supplier financing outlasts the inventory and collection periods combined, and the company runs on money it has not paid out yet.
Working the 40, 30, 25 case
Do it in two steps rather than one, because the two steps answer two different questions and the exam sometimes asks for the first one.
- Operating cycle: 40 + 30 = 70 days
- Cash conversion cycle: 70 − 25 = 45 days
Both numbers usually appear among the choices, along with 95 from adding all three. Read which cycle the question actually named before you pick.
Quick reference
| Measure | Formula | What it answers |
|---|---|---|
| Operating cycle | DOH + DSO | How long from buying inventory to collecting cash |
| Cash conversion cycle | DOH + DSO − DPO | How long the company's own cash is committed |
| Effect of a longer DPO | CCC falls | Suppliers finance more of the gap |
| Negative CCC | Possible | Cash arrives before suppliers are paid |
One caution on the interpretation, since the exam tests it about as often as the formula. A shorter CCC is usually healthier, but a company can shorten it by simply paying suppliers late, which costs it early-payment discounts and eventually goodwill with the people who supply it. So "lower is always better" is a statement worth refusing when a question offers it.
Same shape as the accrued vs. deferred trap. In both, the arithmetic is trivial and the sign carries all the risk, so the fix is to read what the measure means before deciding what to add.
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