Business Finance
DSO Calculator
Measure how many days of credit sales are represented by unpaid invoices at period end. Use the same reporting period for both inputs.
Your result
Days sales outstanding
Enter your period-end receivables, net credit sales and days in the same period.
Calculated on your device. Your numbers aren’t sent or saved.
The method
From receivables to days, then to a terms comparison
Divide period-end accounts receivable by net credit sales during the period, then multiply by the number of days. This period-end DSO approximates the sales time held in receivables. Add usual payment terms to compare that modeled figure with the time customers were given. The receivables gap uses average daily credit sales times the term difference; it does not identify overdue invoices or predict a collection date.
Example 1
Net 30, but 47 modeled days
In a 90-day quarter, $90,000 of net credit sales is $1,000 per day. With $47,000 of unpaid credit invoices at quarter end, DSO is 47 days. Compared with Net 30 terms, the modeled gap is 17 days and $17,000 of receivables. This is a balance comparison under a steady-sales assumption; it is not proof that $17,000 is overdue or immediately collectible.
- Period-end DSO
- 47.00 days
- Gap to Net 30
- +17.00 days
- Modeled receivables gap
- $17,000.00
Example 2
Why cash sales must be excluded
Suppose a business also took $60,000 of cash sales in that quarter. The DSO numerator is still $47,000 in unpaid credit invoices, and the denominator stays $90,000 of net credit sales—not $150,000 of all sales. Including cash sales would misleadingly lower DSO to 28.20 days.
- Credit-sales denominator
- $90,000.00
- Correct DSO
- 47.00 days
- Misleading all-sales DSO
- 28.20 days
Before you calculate
Assumptions & limits
- Use period-end trade receivables from credit invoices, net credit sales after returns and allowances, and the actual days in that same period. Cash sales are excluded. All money is entered and shown in USD with no conversion.
- This is the period-end-balance DSO method. An average-receivables method and invoice-level “true DSO” can give different results, especially when sales are seasonal or growing quickly.
- A single payment term is only a comparison benchmark. Different terms across customers, disputes, write-offs and sales timing can make the aggregate gap diverge from overdue invoice balances.
- The receivables gap assumes a steady credit-sales pace. It can be negative, and it does not mean the amount can be collected immediately. Review invoice aging before changing credit policy.
- Money fields accept 0–999999999.99 with up to two decimals; net credit sales must be positive. Period days accept 1–366 whole days; optional payment terms accept 0–366 whole days. Results round to two decimals, with midpoint ties away from zero.
Keep in mind
Common mix-ups
Including cash sales
Cash paid at sale has no waiting period in receivables. Including it in net credit sales understates DSO.
Mixing a quarter of sales with annual days
Use the same period length as the credit-sales total. A 90-day quarter needs 90 days, not 365.
Reading DSO as overdue days
DSO is an aggregate ratio. Compare it with stated terms for a signal, then use an invoice-aging report to find which accounts are actually late.
Sources & calculation notes
Documents period-end DSO as ending receivables × days ÷ credit sales and notes comparison with credit terms.
Documents regular DSO as total receivables ÷ total credit sales × days.
Calculation and input rules checked: . Engineering validation; no professional accounting review is claimed.