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Interactive calculator

Debtor days calculator

Estimate how long, on average, credit sales remain unpaid.

Last reviewed 1 October 2026

Enter your numbers

Unpaid customer invoices from credit sales.

Exclude cash sales and use the same GST basis as receivables.

For example, 90 for a quarter or 365 for a year.

Your entries are calculated on this device. They are not uploaded or saved.

Illustrative result

Estimated debtor days
15.0 days

Compare this figure with your agreed customer terms and your actual invoice ageing.

How to use this tool

Debtor days = trade receivables ÷ credit sales × days in the period.

A simple example

$35,000 receivables on $210,000 credit sales over 90 days is 15 debtor days.

Assumptions and limits

A period-end snapshot can be distorted by seasonality or a single large invoice. Compare like periods and check invoice ageing.

General information only. Check your own records and speak with a qualified professional where the decision depends on accounting, tax, legal or financial advice.

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