Days payable outstanding, usually shortened to DPO, estimates how long a business takes on average to pay its suppliers. It’s one of the three numbers in the cash conversion cycle, alongside how long customers take to pay you and how long stock sits on the shelf. A higher DPO means you hold on to cash longer. A lower one means you pay faster.
The formula takes one line, but a few choices hidden inside it can move the answer by weeks. For a small business, especially one that doesn’t sell physical products, those choices matter more than the formula itself.
The standard formula
The textbook version divides your accounts payable balance by your cost of goods sold for a period, then multiplies by the number of days in that period. So a business that owes suppliers 40,000 at year end and had 300,000 of cost of goods sold over the year has a DPO of roughly 49 days.
Two small refinements make it more reliable. First, use the average payables balance across the period rather than a single closing figure, since a closing balance can be unusually high or low depending on when a big bill landed. The simplest average is the opening balance plus the closing balance, halved. Second, keep the period consistent. If you use a quarter’s cost of goods sold, use the days in that quarter, not 365.
You can run the numbers with our DPO calculator, which has an option for using the average balance.
Why the formula breaks for service and SaaS businesses
Cost of goods sold works as the bottom half of the formula when most of what you owe suppliers is for the goods you sell. For a retailer, distributor or manufacturer, that’s mostly true.
For a software company, an agency, a consultancy or most service businesses, it isn’t. Cost of goods sold might only include hosting, a few delivery tools and maybe some contractors. Meanwhile accounts payable holds bills for marketing services, software subscriptions, legal fees, rent, freelancers and everything else. You end up dividing a payables balance that includes all your supplier bills by a cost figure that only covers a slice of them, and DPO comes out much higher than how long you actually take to pay.
The usual fix is to replace cost of goods sold with what you actually buy from suppliers on credit over the period. In practice that means cost of goods sold plus the operating expenses that come in as supplier bills: software, marketing services, professional fees, contractors, rent, utilities. Leave out costs that never pass through payables, like salaries, depreciation and card spend that’s settled straight away. The result is sometimes called purchase-based DPO, and it gives a more honest picture of how quickly you pay the people who invoice you.
Whichever version you use, use it every time. A DPO that jumps because you changed the denominator tells you nothing about your payments.
What a reasonable DPO looks like
There isn’t a universal good number, and most published benchmarks are drawn from much larger companies than yours. The Hackett Group’s 2025 Working Capital Survey, for example, reported that DPO rebounded to 59 days across the top 1,000 US-listed non-financial companies. Those are businesses big enough to set payment terms for their suppliers, so it’s not a target for a 20-person company.
A more useful benchmark is your own payment terms. If most of your suppliers give you 30 days and your DPO is 30 to 35, you’re paying roughly on time. If it’s 55, you’re either paying late or carrying old balances that should have been cleared. If it’s 12, you’re paying well before you need to, which may be deliberate (to take an early payment discount or keep a key supplier happy) or may just be habit. Our payment terms calculator helps work out due dates and discount windows for common terms.
Tracking the number month to month tells you more than any single reading. A slow drift upwards with no change in your terms usually means something in the payables process is slowing down.
The invoices your DPO can’t see
DPO is built from your accounts payable balance, and that balance only contains bills that have been entered into your accounting system. Anything still sitting in an inbox, a WhatsApp chat or a pile on someone’s desk isn’t in there yet.
That’s a bigger gap than it sounds. Ardent Partners’ State of ePayables 2025 found that the average invoice takes 13.5 days to process for most organisations, against 2.9 days for the best performers. If a large share of your bills take a couple of weeks to reach the books, your payables balance at any point is missing a chunk of what you actually owe, and your DPO looks lower than it is. You might think you’re paying in 25 days when the real figure, measured from invoice date, is closer to 40.
The same goes in reverse at month end. If a team rushes to enter a backlog of bills just before closing, payables jumps, and DPO looks like it got worse when nothing changed in how you pay.
A few other things distort the number in ways worth knowing about. Disputed invoices sitting unpaid inflate it. Credit notes that haven’t been posted inflate it too, because the balance is higher than what you’ll actually pay. Prepayments and deposits have the opposite effect. And because DPO is an average, one large overdue supplier can move it as much as a deliberate change in policy. When the number moves, look at the aged payables report by supplier before deciding what it means.
What to do with it
For most small businesses, the goal is to pay on the due date. Paying earlier gives away cash for nothing unless there’s a discount or a relationship reason. Paying later than agreed creates friction with suppliers and, in some countries, a legal right for them to charge interest. In the UK, for example, the Late Payment of Commercial Debts (Interest) Act 1998 allows suppliers to claim statutory interest on overdue business invoices.
If you want a higher DPO, the honest route is to negotiate longer terms with suppliers, not to pay late on the terms you already have. Longer terms show up in DPO without damaging the relationship.
Two habits make DPO a number you can trust. Get bills into the accounting system soon after they arrive, so payables reflects what you owe. And review the aged payables report alongside DPO, so you can see which suppliers are behind the average.
Where tools fit
Your accounting system already holds everything needed to calculate DPO, and most produce an aged payables report. For many small businesses that’s enough, as long as bills are entered promptly.
Payment platforms that schedule payments by due date help businesses that want to pay exactly on terms, especially with a lot of suppliers or payment runs across several bank accounts.
Clearline addresses the gap upstream of both. It reads invoices as they arrive by WhatsApp, email or upload and posts approved bills as drafts into the accounting system you already use, so the payables balance, and the DPO built on it, reflects bills you’ve received rather than only the ones someone has had time to type in. Each bill keeps a link back to the message or email it arrived in, which also makes it easier to see how long it took to get from the supplier into the books.