Business calculators
Days sales outstanding calculator.
See how many days of credit sales are sitting uncollected in your receivables.
DSO = accounts receivable ÷ credit sales × days in period. Or use the countback method when sales swing from month to month.
Inputs
Result
Worked example
Receivables of $225,000 against $1,800,000 of annual credit sales: 225,000 ÷ 1,800,000 × 365 = 45.6 days. For countback with $300,000 receivable and monthly credit sales of $150,000 (30 days), $140,000 (31 days) and $130,000 (30 days): the newest month absorbs $150,000 (30 days), the next absorbs $140,000 (31 days), and the remaining $10,000 is 10,000 ÷ 130,000 × 30 = 2.3 days. DSO = 63.3 days.
Formula and sources
The BDC glossary defines the average collection period as the average number of days it takes a business to collect and convert its accounts receivable into cash (checked 2026-09-30). The FDIC Money Smart for Small Business page was also checked and does not state a DSO formula. The formula and the countback method on this page are therefore arithmetic on the definition, not quoted from either source. No benchmark is given, because neither source provides one.
Period alignment
Receivables and credit sales must describe the same business and the same period. Annual sales over a quarter-end balance, or total sales instead of credit sales, will mislead. If sales are growing quickly, simple DSO overstates collection time; countback is less affected by that.
FAQ
What is days sales outstanding?
The average number of days to collect receivables, here receivables ÷ credit sales × days in period.
Should I use total sales or credit sales?
Credit sales. Cash sales never enter receivables, so including them makes DSO look lower than it is.
When is countback better?
When sales are uneven or seasonal, because it matches receivables against the most recent sales instead of a period average.
This is a math tool, not accounting advice.