Days sales outstanding (DSO) is the average number of days a business takes to collect payment after a sale. The standard formula is accounts receivable divided by credit sales for a period, multiplied by the number of days in that period. A business with $240,000 in receivables and $720,000 of credit sales over 90 days has a DSO of 30 days. A rising DSO means cash is arriving later. On payment plans, DSO runs high by design, because installments are owed but not yet due. Track overdue balances alongside it.
What is DSO?
DSO measures how long, on average, it takes you to turn a sale into cash. It is built from two numbers you already have: your accounts receivable balance and your credit sales.
How do you calculate DSO?
DSO = (accounts receivable ÷ credit sales for the period) × days in the period
Use credit sales only. Sales paid in full at checkout never become receivables, so including them makes DSO look better than it is.
What does a DSO example look like?
| Input | Value |
|---|---|
| Accounts receivable at quarter end | $240,000 |
| Credit sales in the quarter | $720,000 |
| Days in the period | 90 |
$240,000 ÷ $720,000 = 0.3333. Multiply by 90 and you get 30 days. On average, it takes this business 30 days to collect a sale.
The same business a quarter later has $300,000 in AR on the same $720,000 of sales. $300,000 ÷ $720,000 = 0.4167. Multiply by 90 and you get 37.5 days. Collections slowed by about a week.
What is a good DSO?
There is no single target. Compare DSO to your own payment terms. If you bill Net 30 and your DSO is 45, customers are paying about two weeks late on average. If it's 31, they pay close to on time. The trend over several months tells you more than any one figure.
Why does DSO look high on a payment plan?
A payment plan keeps a balance open on purpose. Take one $14,800 sale with a $1,500 deposit and twelve monthly payments: eleven of $1,108.33 and a last one of $1,108.37. Right after sign-up, $13,300 is still owed, but none of it is late.
If your books carry that whole $13,300 as a receivable, DSO counts it as slow money. A business that sells mostly on plans can show a DSO of several months while every customer pays on time. Whether the balance sits in AR or as deferred revenue depends on how your accountant books the sale.
For plan-heavy businesses, two measures help:
- Overdue DSO. Run the formula on past-due balances only, so it shows lateness, not the plan length.
- The aging report. AR aging separates current installments from missed ones.
How do you lower DSO?
- Collect a deposit at the start.
- Bill promptly and state the due date on every invoice.
- Send payment reminders before and after due dates.
- Offer autopay so payments don't wait on the customer.
- Follow up on the 1–30 day bucket before balances age further.
Shorter plan frequencies change the picture too. A biweekly plan collects the same total in smaller, more frequent payments.
DSO is standard arithmetic. The figures above are worked examples, and no outside rule sets a target DSO.
Every figure on this page was checked against these sources on Oct 6, 2026. General information, not legal or tax advice.