Online Receipt Generator
Accounts Receivable

DSO Calculator

Calculate Days Sales Outstanding, plus best-possible DSO and average days delinquent.

Result

Best possible DSO

9 days

Average days delinquent

6 days

Days Sales Outstanding

15 days

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How it's calculated

DSO = receivables ÷ credit sales × days in period. Best possible DSO uses only current (not-yet-due) receivables, so it shows what your terms alone would give. The gap between them is average days delinquent — the part caused by late payers.

Days sales outstanding (DSO) is the average number of days it takes to collect payment after a credit sale. This calculator also gives best possible DSO and average days delinquent. Together they show how much of your wait comes from your terms and how much comes from late payers.

The formula

DSO                    = accounts receivable / credit sales x days in period
Best possible DSO      = current receivables / credit sales x days in period
Average days delinquent = DSO - best possible DSO

If credit sales are zero, the calculator returns zero. Average days delinquent never goes below zero.

Worked example

A company reviews one quarter:

  • Accounts receivable: $50,000
  • Current (not yet due) receivables: $30,000
  • Credit sales: $300,000
  • Period: 90 days

DSO: $50,000 / $300,000 x 90 = 15 days

Best possible DSO: $30,000 / $300,000 x 90 = 9 days

Average days delinquent: 15 - 9 = 6 days

The terms alone would give 9 days. Late payers add 6 more.

How to read the result

Compare DSO with your payment terms. A DSO far above your terms means invoices stay open too long. Look at the delinquent days first. They show the part you can change with reminders and follow-up.

Watch for these pitfalls:

  • Period length. A 30-day period and a 90-day period give different DSO for the same data. Compare like with like.
  • Growing sales. Fast growth raises receivables before payments arrive. DSO can rise without a collection problem.
  • Seasonality. A busy month at the end of the period inflates receivables. Check several periods.
  • Credit sales only. Cash sales belong outside this formula.

Methods differ between companies and countries. Confirm your method with an accountant. The guide on days sales outstanding explains the metric in more depth.

Related tools

Frequently asked questions

How do you calculate days sales outstanding?
Divide accounts receivable by credit sales for the period. Then multiply by the number of days in that period. For a 90-day quarter with $50,000 in receivables and $300,000 in credit sales, DSO is 15 days.
What is best possible DSO?
Best possible DSO uses only current receivables, which are invoices not yet due. It shows the DSO you would have if every customer paid exactly on time. It is a floor that your terms set.
What is average days delinquent?
It is DSO minus best possible DSO. The result shows how many days late payers add to your collection time. A value near zero means customers pay close to the due date.
What is a good DSO?
There is no single answer. A good DSO sits close to your payment terms, and norms differ by industry. Compare your number with your own trend and with your terms rather than with a general target.
Which period should I use?
Use a month, a quarter or a year, and match the days to the period. Use 30, 90 or 365. Keep the period the same each time so your results are comparable.