Total unpaid invoices owed to you right now.
Total sales over the year (ideally credit sales).
At 34 days you're a little beyond typical 30-day terms. Tightening collection to 30 days would release around £5,548.
Cash tied up in unpaid invoices
What you'd have tied up at tighter payment terms.
How debtor days are calculated
Debtor days — also called Days Sales Outstanding (DSO) — is the average time customers take to pay you. It turns your outstanding invoices into a number of days' worth of sales.
Daily sales = Annual revenue ÷ 365
Debtor days = Accounts receivable ÷ Daily sales
Why it matters
Every day a customer doesn't pay is a day your cash sits in someone else's account. High debtor days quietly starve a growing business of cash even when it's profitable. Cutting the number frees up money you've already earned — often faster and cheaper than borrowing it.
Frequently asked questions
What counts as accounts receivable?
The total value of invoices you've issued but not yet been paid for — money owed to you by customers on credit terms. Use the current outstanding balance from your accounts.
What are good debtor days?
It depends on your payment terms. If you invoice on 30-day terms, debtor days near 30 is healthy; well above that means customers are paying late or terms are too loose. Compare against your own terms, not a universal number.
How do I reduce debtor days?
Invoice promptly, state clear terms, chase before and on the due date, offer easy payment methods, and consider small early-payment incentives or deposits for large jobs. Even a few days' improvement releases real cash.
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These calculators are for general guidance only and use the figures you enter. They are not financial, accounting or tax advice. Always check important decisions with a qualified professional.