Finance template

Mortgage Overpayment Calculator

What an extra amount each month actually buys you — the interest saved and the years knocked off.

$19one payment, yours to keep

✓Instant download
✓Every later version free
✓Commercial use
✓No signup, no watermark

95: live formulas, each one recalculated and checked
8: columns: Year, Opening balance, Paid in year, Interest, Principal repaid, Closing balance, Closing without overpaying, Ahead by
15: figures worked out for you

A homeowner deciding whether to overpay — usually looking for this when spare money each month and a choice between saving and overpaying.

Need more than one? All 11 Finance templates for $39 — $176 bought separately. All 66 for $99.

Works in Excel 2013 and later, Microsoft 365, Google Sheets and LibreOffice Calc. Set up to print landscape on one page wide. Version 1, updated 25 September 2026.

There are free templates. Why this one?

There are, and some are fine. The difference is what has been checked. This file was built from scratch, then every formula in it was recalculated by a separate checker that compares each result against an independently worked-out answer — 95 of them here. A template that looks right and totals wrong is worse than no template at all, and that is the usual failing of one downloaded from a search result.

It also opens with sample rows already filled in, so you can see every formula working before you touch it, and it is set up to print without fighting the page setup. No email wall, no signup, no watermark, and you can use it commercially.

About this Mortgage Overpayment Calculator template

Overpaying a mortgage reduces the balance that interest is charged on, which cuts both the total interest and the time left to pay. This Excel mortgage overpayment calculator uses your balance, interest rate, remaining term and monthly overpayment to show exactly what the extra money buys you.

A year-by-year schedule compares your balance with and without overpaying, and the summary shows the months and years saved, the interest saved and how much you save for every £1 overpaid.

Good for

→Deciding whether to overpay your mortgage or save instead
→Seeing how much a small monthly overpayment saves over the term
→Comparing overpayment amounts before changing a standing order

What it works out for you

What overpaying buys you

→Normal monthly payment
→You would actually pay
→Months left at the normal payment
→Months left when overpaying
→Months saved
→Years saved
→Interest paid without overpaying
→Interest paid when overpaying
→Interest saved
→Extra paid in over the term
→Saved per £1 overpaid

What is inside the Mortgage Overpayment Calculator template

The table has 8 columns. Calculated columns fill themselves in; the rest are yours to type over.

→Year
→Opening balance
→Paid in year
→Interest
→Principal repaid
→Closing balance
→Closing without overpaying
→Ahead by

Settings in the “Loan” box

→Amount outstanding
→Annual interest rate
→Years left to run
→Extra paid each month

How to use the Mortgage Overpayment Calculator in Excel

Change the four figures in the Loan box and everything re-runs. The last column is the balance you would have had without overpaying, so the gap is the whole point.

The file opens with sample rows so you can see every formula working before you change anything. Type your own figures over them. When you need more rows, insert them inside the existing block rather than underneath it, so the totals keep covering every row.

Shaded, boxed cells below the table are settings the formulas read from. Change those first — every row that depends on them updates at once.

Functions and formulas it uses

Every one of these exists in Excel, Google Sheets and LibreOffice, so the file behaves the same wherever you open it.

FVIFERRORMAXMINNPERPMT

Questions about the Mortgage Overpayment Calculator

How does it work out the time saved?

It uses Excel's NPER function to find how many months the mortgage takes with the higher payment, and compares that with the months left on your normal payment.