DSO Definition
Days Sales Outstanding (DSO) is the average number of days a company takes to collect payment after a credit sale is made. It is the most widely used accounts receivable efficiency metric, expressed as a single number of days. A lower DSO means customers pay quickly and cash converts fast; a higher DSO means cash is tied up in unpaid invoices and working capital is under pressure.
DSO is calculated by dividing accounts receivable by total credit sales over a period, then multiplying by the number of days in that period. Finance teams track it monthly or quarterly to gauge collections health, forecast cash flow, and benchmark against industry norms. Because it normalizes for revenue size, DSO lets a $2M company and a $200M company compare collection efficiency on the same scale.
Also referred to as: DSO, days sales outstanding, average collection period, receivable days.
The DSO Formula
DSO = (Accounts Receivable ÷ Total Credit Sales) × Number of Days
Use net credit sales (exclude cash sales) and match the day count to your period — 365 for a year, 90 or 91 for a quarter, ~30 for a month.
Example: A SaaS company has $500,000 in accounts receivable and $3,000,000 in credit sales over the last 365 days. DSO = ($500,000 ÷ $3,000,000) × 365 = 60.8 days. On average, it takes that company about 61 days to collect after invoicing.
What counts as a good DSO?
There is no universal target — a "good" DSO depends on your payment terms and industry. A reasonable rule of thumb is that DSO should not exceed roughly 1.5× your standard payment terms. If you bill Net 30, a DSO under 45 days is healthy; consistently above 45 signals collection friction.
B2B SaaS and professional services typically run DSO between 40 and 70 days. Industries with longer contractual terms — construction, manufacturing, enterprise software — often see 60 to 90+ days as normal. The trend matters more than the absolute number: a DSO climbing month over month is an early warning that collections are slipping or that newer customers are paying slower.
How to reduce DSO
The fastest levers are operational, not contractual. Invoice the day terms are met rather than batching at month-end, because every day an invoice sits uncreated is a day added to DSO. Send invoices to the right accounts-payable contact in the format their system expects, and confirm receipt.
Automate dunning so reminders go out before and after the due date without anyone remembering to send them. Offer early-payment incentives such as 2/10 Net 30 where margins allow. Finally, apply incoming cash promptly — an unmatched payment sitting in a suspense account still shows as outstanding receivable and inflates DSO even though the customer has already paid.
When you'd use this
- Reporting collections efficiency to leadership, a board, or investors.
- Forecasting cash flow and working-capital needs.
- Benchmarking your AR performance against industry peers.
- Diagnosing whether a cash-flow problem is a collections problem or a sales problem.
DSO FAQ
What is the formula for DSO?
DSO = (Accounts Receivable ÷ Total Credit Sales) × Number of Days in the period. For an annual figure, use 365 days. For example, $500,000 in receivables on $3,000,000 of annual credit sales gives a DSO of about 61 days.
What is a good DSO?
A good DSO is generally no more than about 1.5 times your payment terms. If you bill Net 30, a DSO under 45 days is healthy. Most B2B SaaS and services companies run between 40 and 70 days, but the right target depends on your industry and contractual terms.
Why is my DSO increasing?
A rising DSO usually means one of three things: invoices are being created or sent late, collections follow-up is inconsistent, or newer customers are slower payers than your historical base. Unapplied cash sitting in suspense accounts can also inflate DSO even after customers have paid.
What is the difference between DSO and the average collection period?
They are the same metric. "Average collection period" is the descriptive name for what DSO measures — the average number of days between a credit sale and cash collection.