In short: Days sales outstanding (DSO) is the average number of days it takes to collect payment after a sale on credit. The formula is (accounts receivable ÷ credit sales) × days in the period. A business with £250,000 GBP in receivables and £1.5 million GBP of annual credit sales has a DSO of 61 days.
The number only means something next to your payment terms. A DSO of 55 days on 60-day terms is healthy. A DSO of 45 days on 30-day terms is not.
DSO is the standard measure of how quickly a business turns credit sales into cash. It is also one of the easiest metrics to calculate incorrectly, and one of the easiest to misread once calculated correctly.
This guide covers the formula and a worked example, what the published benchmarks actually say, the specific ways the number misleads, and what measurably moves it.
The DSO formula
The standard calculation is:
DSO = (accounts receivable ÷ credit sales) × number of days in the period
Worked example. A business finishes the year with £250,000 GBP of trade receivables on £1.5 million GBP of annual credit sales:
- 250,000 ÷ 1,500,000 = 0.1667
- 0.1667 × 365 = 61 days
The same business measuring a single month, with £250,000 GBP of receivables against £140,000 GBP of credit sales in that month, gets (250,000 ÷ 140,000) × 30 = 54 days. Two different answers from the same ledger, both arithmetically correct. Which one is right depends on questions covered further down.
Three inputs decide whether the answer means anything:
- Use average receivables, not the closing balance. Opening plus closing, divided by two. A single period-end snapshot inherits whatever happened to land in the last week.
- Use credit sales, not total revenue. Including cash sales inflates the denominator and understates DSO, making collections look better than they are.
- Match the periods. Receivables and sales must cover the same window and the same basis. Receivables including VAT measured against revenue excluding VAT will overstate DSO every time.
What counts as a good DSO
Allianz Trade, which aggregates financial-statement data from more than 75,000 corporate customers worldwide, put the global average DSO at approximately 62 days in 2024, an increase of two days year on year (2025 Global DSO & Working Capital Report, June 2025). Asia-Pacific was highest at 66 days in the fourth quarter of 2024. Global working capital requirements reached 78 days, the highest since 2008.
The Association for Financial Professionals suggests companies should aim for a DSO below 45 days (2024).
Treat both as orientation rather than a target. Two cautions matter more than the numbers themselves.
First, read DSO against your own terms. A business on 60-day terms with a DSO of 55 days is collecting slightly early. A business on 30-day terms with a DSO of 45 days is collecting fifteen days late, despite the lower headline figure. The gap between DSO and terms is the number that describes performance; DSO alone describes structure.
Put next to each other, the same three businesses rank in a different order depending on which number you look at:
| Business | Terms | DSO | Gap to terms |
|---|---|---|---|
| A | 60 days | 55 days | 5 days early. Collecting well. |
| B | 30 days | 45 days | 15 days late, despite the lower DSO. |
| C | 14 days | 32 days | 18 days late, and the worst of the three. |
Ranked by DSO, business C looks strongest and A looks weakest. Ranked by the gap to terms, the order reverses completely. If you track one number every month, track the gap.
Terms themselves have been broadly stable: Allianz Trade put global average payment terms at 56.5 days in 2025, roughly where they have sat since 2022 and still about three days below the pre-pandemic norm. So where DSO has drifted upward, the cause is generally collection behaviour rather than businesses agreeing longer terms.
Second, be careful comparing across industries. Sector averages reflect how each sector bills, not how well it collects. UK government analysis of payment practices reporting found average payment times of 37 days across all sectors, ranging from 21 days in banking to 53 days in pharmaceutical (Prompt Payment and Cash Flow Review, 2023). A pharmaceutical supplier is not underperforming a bank by 32 days.
A note on what you will not find here. No organisation publishing primary research appears to disclose an average DSO figure specifically for the UK or Western Europe in days. Figures circulating for UK sector DSO generally trace back to vendor compilations rather than original surveys, so they are not reproduced here.
The UK problem, in the government's own numbers
The UK's difficulty is visible in the gap between what is agreed and what happens. Government analysis put the UK average contractual payment term at 41 days while the average time actually taken to pay was 58 days, the longest of the four countries compared (Prompt Payment and Cash Flow Review, 2023):
| Country | Average payment terms | Average time to pay |
|---|---|---|
| United Kingdom | 41 days | 58 days |
| France | 40 days | 57 days |
| Italy | 40 days | 56 days |
| Germany | 42 days | 56 days |
Atradius, surveying B2B companies between the end of the first quarter and the beginning of the second quarter of 2025, found 51% of UK B2B invoices overdue and bad debts at 7% of all B2B invoices. Across Western Europe the overdue share was 47% with bad debts at 6%, on terms that mostly ran between 31 and 60 days (Payment Practices Barometer, 2025).
The Federation of Small Businesses found 52% of small businesses had experienced late payment, with 25% reporting an increase (Time is Money, March 2023). Government analysis put the average amount owed to an SME in late payments at £22,000 GBP in 2022.
Five ways DSO misleads you
- Seasonality distorts it in both directions. After a peak trading month, receivables are high against an annual revenue denominator, so DSO reads high even though almost nothing is overdue. After a quiet period, receivables stay high relative to depressed sales, so DSO rises when the real problem is the sales line, not collections.
- The aggregate hides the distribution. Atradius found that late payment and bad debts concentrate in particular sectors and customer segments rather than spreading evenly. A respectable DSO can sit on top of a ledger where a handful of accounts are months overdue and everyone else pays early. The average conceals exactly the accounts you need to see.
- Changing your terms breaks the time series. Move from 30-day to 14-day terms and DSO falls, which looks like an improvement even if customers are now paying relatively later against the new deadline. Compare the gap to terms, not the raw figure, whenever terms have changed.
- Disputed invoices distort the ageing. If disputed amounts sit in the ledger alongside genuinely overdue ones, DSO rises for reasons chasing cannot fix. Separating them is what tells you whether you have a collections problem or an invoicing problem.
- DSO says nothing about what you never collect. Bad debts are written off and leave receivables, so they quietly improve DSO. A falling DSO alongside a rising write-off rate is not an improvement. Read it next to the bad debt ratio.
Best possible DSO: separating structure from behaviour
One variant is worth calculating alongside the standard figure. Best possible DSO uses only receivables that are still within terms:
Best possible DSO = (current receivables ÷ credit sales) × days in the period
Using the earlier example, if £120,000 GBP of that £250,000 GBP is still within terms: (120,000 ÷ 1,500,000) × 365 = 29 days.
The comparison is the useful part. Standard DSO of 61 against a best possible DSO of 29 says the structure of the business is fine and specific customers are late. If both numbers are high and close together, the problem is systemic: terms, invoicing or the chasing process itself. The first calls for account-level intervention, the second for a process change.
What actually reduces DSO
Six levers, roughly in order of how quickly they pay back.
| Lever | What it changes |
|---|---|
| Invoice speed and accuracy | Every day between delivery and invoicing is a day added before the clock even starts. Missing purchase order numbers, wrong prices and unmonitored email addresses convert into disputes that age. |
| Payment friction | Every step between deciding to pay and paying is a delay with no commercial cause. A payment link removes the need to find bank details and rekey them. |
| Reminder cadence | A structured sequence before the due date, on it, and at intervals afterwards. Consistency is what teaches customers where the real deadline sits. |
| Segmentation | Since late payment concentrates in a minority of accounts, treating every customer identically wastes effort on the ones who were always going to pay. |
| Terms and credit policy | Shorter terms narrow the window in which an invoice can go late, provided they are enforceable and realistic for the sector. |
| Early settlement discounts | Typically 1% to 2% for payment within ten days, written as "2/10 net 30". Weigh the margin cost against the financing cost of the receivable. |
Two honest caveats. Published evidence quantifying how far each lever moves DSO is thin, and most of the percentage improvements quoted online come from software vendors describing their own products rather than from independent research. And discounts have a specific failure mode worth watching: customers who were always going to pay on time simply take the discount, while the late payers carry on as before.
See what your DSO looks like once the chasing runs on a schedule instead of a to-do list.
Speak to an expertFrequently asked questions
What is the days sales outstanding formula?
DSO = (accounts receivable ÷ credit sales) × number of days in the period. For an annual figure, use 365 days. Use average receivables rather than the closing balance, and credit sales rather than total revenue, otherwise the result will flatter or distort your collections performance.
What is a good DSO?
The Association for Financial Professionals suggests aiming below 45 days, and Allianz Trade put the global average at approximately 62 days in 2024. But the more useful test is the gap between your DSO and your own payment terms: 55 days on 60-day terms is strong, while 45 days on 30-day terms means most invoices are late.
What is the difference between DSO and days beyond terms?
DSO measures the total time from invoice to payment. Days beyond terms measures only the overdue portion, after the agreed deadline has passed. They are not interchangeable: a days-beyond-terms figure of 20 on 30-day terms implies a total collection period of roughly 50 days.
Why has my DSO gone up when nothing seems to have changed?
The usual culprits are seasonality and mix rather than collections. A busy month leaves high receivables against an annual revenue denominator, and a quiet month leaves receivables high relative to depressed sales. Check whether the invoices driving the increase are actually overdue before treating it as a collections problem.
Should DSO be calculated monthly or annually?
Both, for different purposes. Annual DSO is the comparable figure for reporting and benchmarking. Monthly DSO is more responsive for managing the function, but it is more sensitive to mix, so track the trend across several months rather than reacting to a single one.
What should you measure alongside DSO?
The proportion of invoices paid within terms, the ageing distribution, and the bad debt ratio. DSO alone can improve for bad reasons: writing off an unrecoverable balance removes it from receivables and lowers DSO, which is a deterioration reported as an improvement.
Where to start
Calculate two numbers this week: your DSO and your best possible DSO. If the gap is wide, the problem is specific customers and the fix is segmentation and a firmer cadence for the accounts that need it. If both are high, the problem is structural, and terms, invoicing speed and payment friction are where to look first. Then record the gap between DSO and your payment terms every month, because that single figure tells you more than the headline ever will. Chaser's guide to accounts receivable automation covers how to run the cadence without doing it by hand.
