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Free DSO calculator: calculate your Days Sales Outstanding
Use our free DSO calculator to see how long, on average, it takes your business to collect payment from customers and whether that number is improving or heading the wrong way.
CALCULATE YOUR DSO
Use the DSO calculator
Enter your accounts receivable, total credit sales and the number of days in the reporting period to calculate your Days Sales Outstanding.
DSO Calculator
Enter the total amount of money owed to your company by your customers at the end of the period.
Enter the total amount of sales made on credit during the period.
Enter the number of days in the period (e.g., 30 for a month, 365 for a year).
DSO Formula
DSO = accounts receivable ÷ credit sales × number of days
For example: if your accounts receivable is £50,000, credit sales for the period are £100,000, and the period is 30 days:
£50,000 ÷ £100,000 × 30 = 15 days
Your business is taking approximately 15 days, on average, to collect its credit sales.
What your DSO result means
Your Days Sales Outstanding shows the average number of days represented by customer balances that remain unpaid.
There isn’t one perfect DSO for every business. Your payment terms, industry and customer mix all matter. The more useful comparison is how your DSO compares with your agreed terms and whether it is rising or falling over time.
Why DSO matters
Sales can look healthy while a growing amount of cash remains tied up in accounts receivable.
As DSO rises, the business waits longer for cash to return. That can put pressure on working capital, supplier payments, payroll, VAT and investment decisions.
Healthy revenue feels considerably less healthy when too much of it is still sitting on the aged debtor report.
WHAT SITS BEHIND THE NUMBER
What causes a high DSO?
A high or rising DSO often points to weaknesses somewhere in the credit control process:
- Payment terms aren’t clear from the outset
- Invoices are sent late, incorrectly or to the wrong person
- Purchase orders or other payment requirements are missed
- Queries and disputes take too long to resolve
- Chasing is inconsistent or nobody clearly owns it
- Payment promises aren’t followed up
- Payment plans and overdue accounts are escalated too slowly
DSO becomes much more useful when you look at it alongside your aged debtor report and customer payment behaviour. Together, they show both how long cash is sitting in receivables and where the underlying credit control problem may lie.
THE SCALE OF LATE PAYMENT
Late payment is tying up billions in UK businesses
Recent Sage and CEBR research found 44% of invoices were paid late, with an estimated £112 billion tied up in overdue invoices.
Government-backed research also estimates businesses are owed £26 billion in late payments at any given time, while affected businesses spend an average of 86 hours a year chasing payment.
Your DSO brings that wider problem back to one useful question: how much of your own cash is taking longer than it should to arrive?
How to reduce DSO
A high or rising DSO usually isn’t fixed by simply sending more reminder emails. Start by checking what happens before and after an invoice becomes due.
- Was it sent correctly and on time?
- Does Accounts Payable have everything they need?
- Are queries dealt with quickly?
- Are payment promises recorded and followed up?
- Does everybody know when an account needs firmer action?
Fixing those gaps can improve the way money moves through the business and reduce the same late-payment problems recurring.
FIND THE RIGHT NEXT STEP
If your DSO needs attention, start here
Your result can point to several different problems. Collect Wise gives you a clear route depending on what’s happening in your business now.
Aged debt action plan
Several invoices are already overdue.
Review the aged debt, prioritise the accounts and get a clear 30-day action plan.
Credit control review & setup
Late payment keeps repeating.
Review the process behind payment terms, invoicing, chasing, disputes and escalation.
Credit control
training
Your team needs stronger collection skills.
Practical training for staff responsible for chasing payment and handling difficult customer conversations.
Things You Need to know
Frequently Asked Questions
What is a DSO calculator?
A DSO calculator estimates Days Sales Outstanding using your accounts receivable, credit sales and reporting period. It helps show how much of your sales remains tied up in receivables.
What does DSO mean?
DSO stands for Days Sales Outstanding. It measures the relationship between outstanding receivables and credit sales over a period.
How do you calculate DSO?
Divide accounts receivable by credit sales for the period, then multiply by the number of days in that period.
What is a good DSO?
There isn’t one ideal DSO for every business. Compare your result with your payment terms, customer mix, sector and previous results. A DSO that keeps increasing is often more significant than an arbitrary benchmark.
Is DSO the same as debtor days?
They are often used interchangeably. Both are used to understand how much time sales are spending in accounts receivable before cash is collected.
What does a high DSO mean?
Customers may be taking longer to pay. It can also point to weak payment terms, invoice queries, inconsistent chasing, poor credit control or late escalation.
How can I reduce DSO?
Start by reviewing payment terms, invoicing, customer onboarding, query handling, chasing and escalation. If late payment keeps repeating, the underlying credit control process may need attention.
Is DSO the same as aged debt?
No. DSO measures the relationship between outstanding receivables and sales across a period. An aged debtor report shows which specific invoices remain unpaid and how long they have been outstanding.
Can Collect Wise help reduce DSO?
Yes. Collect Wise helps SMEs review aged debt, improve credit control processes, set up clearer chasing routines and train teams responsible for collecting payment.