Average days to pay is a field that exists on customer cards under the history tab (the far right tab when you are looking at a customer card). It gives an indication of how long it takes that particular customer to pay their invoices.

Average days to pay = the total number of days to pay divided by the number of closed invoices.

For Example: Your closed invoices report shows 3 closed invoices for a customer.

Invoice 1 was paid 5 days after the invoice date.

Invoice 2 was paid 10 days after the invoice date.

Invoice 3 was paid 15 days after the invoice date.

Total days 'til paid is 30.

Divide this figure by the number of closed invoices - 30/3 - equals 10 as the average days to pay.

If you enter the payment while you are entering the invoice, using the 'paid today' feature, this invoice would have a 0 days 'til paid. If you combine this with an invoice that was paid 8 days after invoice date - then the average days 'til paid becomes 4. (8 total days divided by 2 closed invoices)