Days sales outstanding (DSO)

What is days sales outstanding (DSO)?

Days sales outstanding is the average number of days it takes to collect cash after you invoice a customer. It turns your accounts receivable into a time figure, showing how quickly sales convert to cash. Lower DSO means faster collections and healthier cash flow; rising DSO signals collection or credit problems.

Formula

Worked example

Benchmarks by stage

How to calculate DSO, step by step

The arithmetic is three inputs, but two of them are where the number usually goes wrong.

1. Pick the period. Monthly is the working cadence for most companies; quarterly smooths seasonal noise. Use the same period every time, because DSO is only readable as a trend.
2. Take ending accounts receivable from the balance sheet at the close of that period. Use gross AR before the allowance for doubtful accounts, or you will flatter the number exactly when collections are deteriorating.
3. Take credit sales for the same period, not total revenue. Any revenue collected at the point of sale — self-serve card payments, app-store billing — never sits in AR, so including it in the denominator pushes DSO artificially low.
4. Divide, then multiply by the days in the period. $150,000 ÷ $600,000 = 0.25, and 0.25 × 90 = 22.5 days.

Two refinements are worth knowing. Average AR — opening plus closing, divided by two — is the more defensible input when receivables moved a lot inside the period, which is normal for a company growing 15% a month. And countback (or roll-back) DSO works backwards through the most recent months' sales until the AR balance is used up, which is the method to reach for when growth is fast enough that a simple average lags reality.

Benchmarks by billing model

There is no universal good DSO, because the number is mostly determined by how you bill before anyone in your company touches a collections process. Compare against your own terms and your own model first, and against an industry median second.

Read the table as terms plus friction. If you invoice net-30 and run a DSO of 38, you have roughly eight days of friction, which is normal. At 55 you have 25 days of friction, and that is a process problem rather than a customer problem. The best possible DSO — what you would collect in if nobody paid late — is the benchmark that actually isolates your own performance from your billing terms.

How to reduce DSO: the playbook

Ordered by how much they move the number for a typical B2B company, not by how satisfying they are to implement. The first two are worth more than the rest combined.

1. Invoice on the day, not at month end

The clock starts when the invoice is issued, not when the work is done or the contract is signed. A company that batches invoicing to the last day of the month adds an average of fifteen days to DSO before a single customer has done anything wrong. Invoicing on the contract date is the cheapest DSO reduction available, and it usually requires no negotiation with anyone.

2. Fix what is on the invoice

A material share of late payments are not late payments at all — they are invoices an AP department could not process. The usual causes are a missing PO number, the wrong billing contact, a line item that does not match the contract, or no remittance instructions. Each one sends the invoice into a queue that nobody is measuring.

• Capture the PO number and the AP contact at contract signature, not at first invoice.
• Send to an AP inbox as well as the champion, since the champion is the person most likely to be on holiday.
• Match line items to the contract's wording exactly, so nothing needs a human to reconcile.
• Put payment instructions and accepted methods on the invoice itself.

3. Run a dunning schedule, and run it before the due date

Most collections processes start when an invoice is already late, which is the point at which it has entered somebody else's payment run and cannot move until the next one. A schedule that touches the invoice seven days before the due date catches the processing problems while they are still fixable: seven days before, on the due date, then at seven, fourteen and thirty days past. Automate the first three and escalate the last two to a named person.

4. Change the terms rather than chasing them

Annual prepayment at a discount converts twelve collection events into one and usually improves both DSO and runway more than any process change. An early-payment discount (2/10 net 30 — two per cent off if paid within ten days) is expensive in annualised terms, so price it deliberately: that discount costs roughly 36% a year, which is worth paying only when cash is genuinely the binding constraint.

5. Make it someone's number

DSO deteriorates quietly because it belongs to nobody. Put ageing on the monthly close checklist with a named owner, review anything over sixty days line by line, and give sales visibility of their own accounts' payment behaviour before the next renewal is negotiated.

What DSO does not tell you

DSO is an average, and averages hide the thing you most need to see. Three limits are worth holding in mind before acting on a movement in the number.

• One large account can be the whole story. A single $200,000 invoice at 90 days can swamp forty healthy small ones. Always read DSO next to an AR ageing report, which shows the distribution the average is concealing.
• It says nothing about collectability. An invoice at 120 days and an invoice at 30 days both count as receivable. DSO tracks speed, not whether the money is coming at all; that is what the allowance for doubtful accounts and your write-off history are for.
• Growth flatters it. As above: a rising denominator pulls DSO down while collections are unchanged or worsening. Check the direction of your growth rate before congratulating anyone on an improvement.

The complementary metrics are days payable outstanding on the other side of the ledger and the cash conversion cycle, which nets the two against inventory. For a software company with no inventory, DSO minus DPO is close enough to the whole working-capital picture.

Why it matters for fast-growing companies

DSO is a direct read on how long your cash sits in customers' hands instead of your bank account. Rising DSO ties up working capital and can force you to raise money you wouldn't otherwise need — at $600,000 a quarter in credit sales, ten days of DSO is about $66,000. Founders should track it monthly alongside an ageing report, and tighten invoicing timing, dunning, and credit checks when it creeps up.

Related terms

Frequently asked questions