What is DSO (days sales outstanding) and how to lower it
The cash-flow metric that tells you how long your money sits in someone else's account — how to calculate it, and how to bring it down.
The definition
Days sales outstanding (DSO) is the average number of days it takes a business to collect payment after making a sale on credit. It measures the gap between delivering work and actually being paid for it. A lower DSO means cash comes in quickly; a higher or rising DSO means money you’ve earned is sitting unpaid — and it’s often the first metric to flag that collections are slipping.
The DSO formula
DSO is calculated over a period — a month, a quarter, a year — like this:
DSO = (Accounts Receivable ÷ Total Credit Sales) × Days in Period
A worked example: say you have $60,000 in outstanding receivables, against $180,000 of credit sales over a 90-day quarter. Your DSO is:
(60,000 ÷ 180,000) × 90 = 30 days
So on average it takes 30 days to collect. Always read DSO against your payment terms. Thirty days is excellent on net-30 terms and a warning sign on net-15. Use the same period length each time so you’re tracking a real trend, not a calendar quirk.
What counts as a good DSO
There’s no universal target — it’s relative to the terms you offer. A useful benchmark is that DSO running more than roughly a third above your standard terms points to a collections problem worth fixing. On net-30, a DSO drifting past 40 days means invoices are consistently landing late.
Some external drag is normal. Around half of US B2B invoices are paid late, arriving about 20 days past the due date on average (Atradius, 2024), and average B2B payment terms in Western Europe have climbed to 52 days from invoicing (Atradius, 2024). The point of tracking DSO isn’t to hit a magic number — it’s to see the trend and act before it runs away from you.
How to lower your DSO
You don’t need to tighten your terms or strong-arm clients to bring DSO down. The practical levers are about making collection reliable:
- Invoice promptly and clearly. The clock starts at the invoice date — send it the moment work ships, with the due date and payment method unmissable.
- Remind before the due date. A friendly nudge a few days ahead prevents the “I forgot” lateness that inflates DSO for no good reason.
- Follow up consistently on overdue invoices. The biggest driver of a high DSO is usually reminders that simply don’t get sent. Automating them so they fire every time removes the human bottleneck.
- Track every promised payment date. When a client says “we’ll pay Friday,” hold that date and follow up the moment it slips — a payment promise you don’t track is a payment you don’t collect.
- Make paying frictionless. Clear terms and easy payment options shave days off the cycle. The UK government cites Sage research that e-invoicing alone can reduce late payments by 20% and cut processing times by 44%.
Where Grace Period fits
Most of what pushes DSO up is follow-up that never happens. Grace Period closes that gap: it connects to your books, drafts human reminders on a schedule you set, and reads each reply. A promise to pay is held to the exact date the client gave, automatically, and the follow-up is drafted the moment that date passes. Consistent, reply-aware chasing shortens the collection cycle without changing a single term — and it never touches or lends your money.
Frequently asked questions
What is days sales outstanding (DSO)?+
DSO is the average number of days it takes a business to collect payment after making a sale on credit. It's a standard cash-flow metric: a lower DSO means you're turning invoiced work into cash faster, and a rising DSO is an early warning that collections are slipping.
How do you calculate DSO?+
DSO = (accounts receivable ÷ total credit sales) × number of days in the period. For example, if you have $60,000 in outstanding receivables against $180,000 of credit sales over a 90-day quarter, DSO is (60,000 ÷ 180,000) × 90 = 30 days. Use the same period consistently so the trend is comparable.
What is a good DSO?+
It depends on your payment terms — DSO should be read against them, not in isolation. If you invoice net-30, a DSO in the low-to-mid 30s is healthy. A common rule of thumb is that a DSO more than about a third above your standard terms signals a collections problem. For context, average B2B payment terms in Western Europe rose to 52 days from invoicing (Atradius, 2024).
Why does DSO matter for an agency?+
Agencies run on project cash flow, so the gap between finishing work and being paid is money you can't use — to make payroll, take the next project, or invest. A high DSO ties up cash you've technically already earned. Around half of US B2B invoices are paid late, landing about 20 days past due on average (Atradius, 2024), which pushes DSO up.
What's the fastest way to lower DSO?+
Consistent, timely follow-up on overdue invoices — because the biggest source of a high DSO is usually reminders that don't go out. Automating reminders so they fire reliably, inviting payment before the due date, and tracking each promised payment date all shorten the collection cycle without changing your terms.
Related reading: what is AR automation · what is a payment promise · best invoice-chasing software for agencies.