Days sales outstanding (DSO) explained

2 min read

(Receivables ÷ sales) × daysThe formula

Days to get paidWhat it measures

Lower frees cashWhy it matters

What DSO measures

Days sales outstanding (DSO) is the average number of days between raising an invoice and the cash landing in your account. It captures how efficiently you turn credit sales into cash. A low DSO means customers pay quickly and your cash recycles fast; a high DSO means money is stuck in the sales ledger, tying up working capital you could otherwise use. It is one of the three building blocks of the cash conversion cycle.

How to calculate it

The standard formula is:

DSO = (average accounts receivable ÷ total credit sales) × number of days in the period.

For a full year, say you carry £120,000 of receivables on average against £1,000,000 of annual credit sales: (120,000 ÷ 1,000,000) × 365 = 43.8 days. So on average customers take just under 44 days to pay. Only count credit sales — cash sales settle immediately and would understate the true figure. Tracking DSO month to month matters more than any single reading: a rising trend is an early warning that collections are slipping or a customer is stretching terms.

What a good DSO looks like

There is no universal target, because it depends on the terms you offer. As a rough rule, a healthy DSO sits close to your stated payment terms: if you invoice on 30 days, a DSO in the low-to-mid 30s is doing well, while 50-plus suggests customers are routinely paying late. The useful comparison is against your own terms and your own history, not a generic benchmark — a 45-day DSO is excellent on 60-day terms and poor on 14-day terms.

Bringing DSO down

Shortening DSO is the cheapest cash you will ever raise, because it costs no interest. Practical levers: invoice the moment work is done, not at month end; state terms and due dates clearly on every invoice; offer easy electronic payment; chase politely but promptly the day an invoice falls overdue; and run credit checks before extending generous terms to new customers. If a structural gap remains — common in B2B trades with long terms — invoice finance advances cash against unpaid invoices, or a revolving line bridges the wait. Model the cash impact of a tighter ledger with the working capital calculator.

Frequently asked questions

What is the difference between DSO and payment terms?

Payment terms are what you ask for — say 30 days. DSO is what actually happens on average. The gap between the two is your late-payment problem: if you invoice on 30 days but your DSO is 48, customers are taking nearly three extra weeks, and that delay is being funded out of your own cash.

Does a high DSO mean my customers are bad payers?

Not necessarily. It can reflect generous terms you chose to offer, a few large slow-paying accounts skewing the average, or simply weak invoicing and chasing. Break the figure down by customer before assuming the worst — often a small number of accounts drive most of the delay.

Can I reduce DSO without upsetting customers?

Yes. Prompt, accurate invoicing and easy payment options remove friction rather than pressure. Early-payment discounts and clear, consistent reminders are normal commercial practice. The aim is to make paying you the path of least resistance, not to strong-arm good customers.