Per-Diem Interest Calculator

Calculate daily mortgage interest and the estimated prepaid-interest collection from closing through the selected interest-paid-through date. The first-payment date is shown as a reasonableness check rather than used to impose a loan-program assumption.

360 or 365 basisShows the exact collection period and day count

Loan and payment information

Loan amount

Note interest rate

Enter 7 for 7.000%.

Closing date

First payment date

Day-count basis

Interest collected through

Commonly the last day of the closing month, but use the actual closing instructions.

Include closing date?

Customer / file name

Property address

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Estimated prepaid interest

Method comparison

Important information

This calculator estimates simple daily interest. It does not determine whether a lender’s closing instructions require an odd-days convention, exclude the closing date, use a different paid-through date, or incorporate interest into another disclosure line. Use the lender’s written instructions for the final settlement figure.