About the DSO Calculator
This DSO calculator measures days sales outstanding — the average number of days it takes your business to turn a credit sale into cash. Enter accounts receivable at the start and end of the period, your credit sales for the same period and the period length, and it returns DSO, accounts receivable turnover and average daily credit sales.
It is built for owners, bookkeepers, controllers and credit managers who want to know whether customers are paying on time. Comparing DSO with your standard payment terms (for example net 30) shows how many days late the average invoice is paid, and how much cash you could free up by collecting on terms.
The calculation uses average receivables ((beginning + ending) ÷ 2) and credit sales only. Cash sales collect immediately, so including them would make DSO look better than it really is. Use the same period for receivables and sales — a quarter of sales with 90 days, a year with 365.
With the default inputs, the days sales outstanding (dso) is 43.8 days. Change any value above to recalculate instantly.
How to use the dso calculator
- 1Enter accounts receivable from your balance sheet at the start and end of the period.
- 2Enter net credit sales for the same period.
- 3Choose the period length that matches the sales figure.
- 4Enter your standard payment terms, such as 30 for net 30.
- 5Compare DSO with your terms and review the cash tied up by late payers.
Formula and method
Average accounts receivable is the mean of the opening and closing balances for the period. Dividing it by credit sales gives the share of the period’s sales still uncollected; multiplying by the number of days in the period converts that share into days. DSO is therefore the same as Days ÷ AR turnover.
Cash tied up beyond terms multiplies the days above your standard terms by average daily credit sales (credit sales ÷ days). It is an estimate of how much receivables would fall if customers paid exactly on time, assuming sales stay constant.
- Average AR
- (Beginning receivables + ending receivables) ÷ 2
- Credit sales
- Net sales made on credit during the same period
- Days
- Length of the period: 365, 90 or 30
Worked examples
Annual DSO for a $1M business
Average receivables are ($110,000 + $130,000) ÷ 2 = $120,000. Dividing by $1,000,000 of credit sales and multiplying by 365 gives a DSO of 43.8 days — 13.8 days beyond net 30 terms. At $2,739.73 of daily credit sales, that is about $37,808 of cash waiting in receivables.
Quarterly DSO
Average receivables of $50,000 against $300,000 of quarterly credit sales is a turnover of 6 times. Over 90 days that is a DSO of 15 days, well inside 30-day terms, so no extra cash is tied up.
Monthly DSO on net 45 terms
With $80,000 in receivables and $60,000 of credit sales in a 30-day month, DSO is 80,000 ÷ 60,000 × 30 = 40 days, five days faster than the 45-day terms.
Frequently asked questions
What is a good DSO?+
A good DSO is close to your payment terms. If you invoice net 30, a DSO in the low 30s means customers pay roughly on time; a DSO well above terms signals slow collections. Norms vary by industry, so compare against peers too.
Should I use total sales or credit sales for DSO?+
Use credit sales. Cash sales are collected immediately and never sit in receivables, so including them lowers DSO and hides collection problems. If you only know total sales, note that your DSO is understated.
What is the difference between DSO and accounts receivable turnover?+
They measure the same thing in different units. AR turnover is how many times receivables are collected in a period; DSO converts that into days by dividing the period length by the turnover ratio.
How can I lower my DSO?+
Invoice immediately, state clear terms, offer early payment discounts such as 2/10 net 30, accept card and ACH payments, send reminders before the due date, and follow up quickly on overdue invoices.
Why use average receivables instead of the ending balance?+
Receivables can swing at period end because of a big invoice or seasonal sales. Averaging the opening and closing balances smooths that out and better matches the sales earned across the whole period.
Results are estimates for educational purposes and are not financial advice. Rates, fees and terms vary — confirm with your lender or a licensed advisor before making decisions.