What is DSO (Days Sales Outstanding)?

DSO stands for Days Sales Outstanding. It is the single clearest number for how long your cash is stuck inside unpaid invoices. A business with a DSO of 45 is, on average, waiting about a month and a half between the moment of sale and the moment the money actually lands in the operating account. That waiting period is the working-capital gap every small business finances out of pocket, whether they think of it that way or not.

The formula is simple: accounts receivable divided by total credit sales, multiplied by the number of days in the period. Many small businesses run 45 to 60 day DSOs without realizing it, because the number never gets calculated until an accountant or a lender asks for it. Once you track it monthly, even small movements become meaningful: a 7-day drop in DSO on a business with steady credit sales frees a real amount of cash with no change in revenue.

DSO matters to collections specifically because the biggest lever to move it is not pricing or sales volume. It is shortening the time between invoice issue and payment, which is precisely what a reliable early-stage collections cadence does. That is why the first question a lender or an AR automation vendor asks is always, what is your current DSO.