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Days Sales Outstanding (DSO) Calculator with Best Possible DSO

DSO measures how long it takes to turn a credit sale into cash. The plain ratio mixes two things: how generous your terms are and how well you collect. Best possible DSO separates them, so you know where to act.

Your numbers

Total receivables at period end

Total open invoices from the AR aging report.

Receivables not yet due

The 'current' bucket of the aging, not past due.

Credit sales in period

Invoiced credit sales for the period, excluding cash sales.

Days in period

Target DSO

40 days

Used for the cash release what-if.

Your results

DSO

40.6452

Average days it takes to collect after a credit sale.

Cash released at target DSO

$88,889

One day of DSO equals one day of credit sales.

Best possible DSO

28.3065

DSO if every past-due invoice were collected, the floor set by your terms.

Average days delinquent

12.3387

The collection problem alone, separated from your payment terms.

Past due balance

$1,700,000

Past due share of AR

30.4%

DSO moves with sales timing. Use the same period length for credit sales and the day count, and compare month to month on a consistent basis.

Save results:

Cash released vs target DSO

Sweeps Target DSO from 15 to 90, holding your other inputs fixed.

Past-due drivers by customer, on demand

Optional: see how a read-only ERP query could surface AR drivers without a monthly export.

Optional. The tool and every export work without this. No spam.

How to use the calculator

Run your AR aging as of period end and read the total and the current bucket. Enter credit sales for the same period, then pick the matching day count. For a quarter, 90 days; for a month, 30. The target DSO slider estimates cash released if you hit that target at the current sales rate, and the chart sweeps the whole range.

Exclude cash and prepaid sales from credit sales
Use invoiced sales, not orders
Match the period to the aging cut-off date

The method

DSO = receivables / credit sales x days in period. Best possible DSO = current receivables / credit sales x days. Average days delinquent = DSO minus best possible DSO. If your terms are net 30 and best possible DSO is 28, there is little room in terms, and the gap sits in collection. If best possible DSO is 45 on net 30 terms, invoicing is probably late or terms are being extended informally.

Reading the result

A high average days delinquent points to dunning, disputes or credit holds. A high best possible DSO points to billing delay, long terms or milestone billing that outpaces collection. Look at the past due share by customer next. Often three or four accounts drive most of the gap, and a single resolved dispute can move DSO by days.

Common mistakes and ERP notes

Do not compare DSO across periods of different length without recalculating. Quarter-end spikes in sales shrink DSO artificially if the sales sit in the last week. Most ERPs give you aging in the AR module, and some offer a DSO or collection effectiveness report, but its definition of sales may differ from yours, so check it.

Credit memos and unapplied cash distort the total
Intercompany balances should be excluded
Foreign currency AR should be converted at period-end rates

Frequently Asked Questions

What is the difference between DSO and best possible DSO?

DSO uses all receivables, so it includes past-due invoices. Best possible DSO uses only the current, not yet due balance. The gap between them, average days delinquent, isolates collection performance from your payment terms.

What is a good DSO?

A common rule of thumb is no more than one-third above your standard terms, so about 40 days on net 30. Industry and customer mix matter a lot, so track your own trend and compare average days delinquent, which is less sensitive to terms.

Does DSO include sales tax?

Receivables usually include tax billed on the invoice, so for a clean ratio use sales including tax, or strip tax from receivables. What matters is consistency between numerator and denominator.

How much cash does one day of DSO represent?

One day of DSO equals credit sales divided by days in the period. For 12.4 million of credit sales over 90 days, that is about 138 thousand dollars per day. The calculator applies this to your target.

If your AR aging is a manual export every month, we can show how a read-only agent over the ERP could list past-due drivers by customer on demand.

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