Debtor days — also called Days Sales Outstanding (DSO) — measures how long, on average, customers take to pay after a credit sale. It’s the metric that turns “our clients pay slowly” from a feeling into a number you can manage.
Debtor Days (DSO) Calculator
How long do customers take to pay you? Enter receivables and credit sales.
The formula
Debtor Days = (Accounts Receivable ÷ Credit Sales) × Number of Days
Use credit sales, not total sales, where cash sales are significant — cash sales have no collection delay and dilute the true picture.
Worked example
| Accounts receivable | $85,000 |
| Annual credit sales | $730,000 |
| Calculation | (85,000 ÷ 730,000) × 365 |
| Debtor days | ≈ 42.5 days |
If payment terms are net-30 and DSO runs 42.5, customers are taking two extra weeks on average — working capital financed by you, interest-free.
Improving the number
DSO falls through mechanics, not hope: invoice immediately on delivery, state due dates as calendar dates, take deposits, make payment one click, and escalate on a schedule. Each day shaved off DSO releases (daily credit sales × 1) of permanent cash back into the business — for the example above, roughly $2,000 per day recovered.
FAQ
What is a good DSO? Compare against your own payment terms and industry norms: DSO near your stated terms (e.g. ~30 days on net-30) is healthy; persistently 10–15+ days beyond terms signals collection problems.
Should I use total sales or credit sales? Credit sales, where possible — cash sales collect instantly and make DSO look artificially better.
What’s the difference between DSO and debtor days? None — they’re two names for the same metric. Accounts receivable days is a third.
How do I reduce debtor days? Immediate invoicing, calendar due dates, deposits, easy payment methods, and a fixed follow-up schedule — process changes, not reminders alone.
Does high DSO affect profit? Not accounting profit directly — but it starves cash flow, increases bad-debt risk, and can force borrowing that does cost real money.