Days sales outstanding estimates the average time between recording sales or invoices and collecting payment.
Definition
Days sales outstanding, or DSO, is a ratio that estimates how many days of sales are represented by accounts receivable. A common calculation divides receivables by sales for a chosen period and multiplies by the number of days in that period. Firms vary in whether they use invoiced sales or recognized revenue, average or ending receivables, and calendar days or another period convention. Those choices, along with client mix, billing schedules, disputed invoices, and payment terms, affect the result. Owners use DSO to monitor cash tied up in unpaid work and to investigate changes in collection timing. It is an average, so it can conceal overdue balances or differences among clients and projects. DSO is not a due date, a measure of profitability, or a direct count of how long each invoice remains unpaid. For related measures, see DSO and cash conversion and how to invoice civil engineering clients.
How owners use it
- Monitor the relationship between receivables and sales over a consistently selected period.
- Compare DSO trends with invoice aging and billing-cycle timing to locate collection delays.
- Example: With $120,000 in receivables and $360,000 in sales over 90 days, DSO is ($120,000 / $360,000) × 90 = 30 days.
- State whether the calculation uses recognized revenue or invoiced sales and whether receivables are an average or period-end balance.
