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Mortgage Overpayment Calculator

See how much time and interest you save by paying extra on your mortgage each month.

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Enter Current balance, Annual interest rate, Remaining years, Extra monthly payment and the Mortgage Overpayment Calculator works out Months saved, Interest saved, New years to payoff straight away. For instance, with Current balance = $150,000.00, Annual interest rate = 3.5%, Remaining years = 20 and Extra monthly payment = $100.00 it returns Months saved = 35, Interest saved = $9,042.62 and New years to payoff = 17.167.

How to use it

  1. Enter your values: Current balance, Annual interest rate, Remaining years, Extra monthly payment.
  2. Read the result instantly: Months saved, Interest saved, New years to payoff.

Frequently asked questions

How does the Mortgage Overpayment Calculator work?

It takes Current balance, Annual interest rate, Remaining years and Extra monthly payment and derives Months saved, Interest saved and New years to payoff from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

4 values: Current balance ($), Annual interest rate (%), Remaining years and Extra monthly payment ($). Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Current balance = $150,000.00, Annual interest rate = 3.5%, Remaining years = 20 and Extra monthly payment = $100.00, the calculator returns Months saved = 35, Interest saved = $9,042.62 and New years to payoff = 17.167. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

How much does the result change with different inputs?

It moves a lot. Using Current balance = $300,000.00, Annual interest rate = 3.9%, Remaining years = 40 and Extra monthly payment = $200.00 instead, Months saved goes from 35 to 129 — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which units should I enter the values in?

Enter Annual interest rate %.

What does it give for smaller values?

Scaled down to Current balance = $75,000.00, Annual interest rate = 3.1%, Remaining years = 10 and Extra monthly payment = $50.00, Months saved comes out at 9. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Before making an offer: what the bank will lend, what the purchase costs on top of the price, and how much deposit closes the gap.

What is the most common mistake?

Budgeting for the price and forgetting the acquisition costs. Notary fees, transfer duty and registration add between 2% and 15% depending on the country — enough to sink an offer.

What is the difference between the Mortgage Overpayment Calculator and the ARM mortgage calculator?

This one returns Months saved and Interest saved; the ARM mortgage calculator returns Initial payment and Max payment after 1st adjustment. That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Mortgage recast calculator is the closest one after this: A recast re-amortises your mortgage after a lump-sum principal payment, keeping the same rate and remaining term but lowering the monthly payment. Enter your current balance, rate, original term, months already paid, the lump sum and any recast fee to see the new payment and the interest you save.

Further reading

All guides →
ExplainerIs a Mortgage Overpayment Worth It?See how overpaying a mortgage cuts total interest and shortens the term, and when investing the same money might beat paying the loan down faster.ComparisonOverpay the Mortgage or Invest the Difference: the Tax That Decides ItOverpaying earns exactly your mortgage rate, certainly and untaxed. An investment must therefore beat that rate divided by one minus the tax on its return — which at a 3.2 % mortgage means 4.57 % in a French ordinary account and 3.20 % inside the German savings allowance, before any reward for taking risk.ComparisonFixed vs Variable Rate Mortgage: Which Should You Choose?Compare fixed and variable rate mortgages on certainty, cost, and risk, and see which suits your budget, timeline, and tolerance for change.ExplainerThe Total Cost of a Loan, ExplainedLearn why a loan costs far more than the amount borrowed, how total interest builds over the term, and why a longer term means paying more.GuideWhen Refinancing a Mortgage Actually Pays: France, Germany, ItalyThe rule of thumb everyone repeats — one point of rate gap — is not a rule and gets the timing wrong. What decides it is how much interest you have not yet paid, and the three countries answer the cost side in three completely different ways. Here is the arithmetic, computed.ExplainerMortgage Points: When Buying Down the Rate Actually PaysOne point on a $300,000 loan costs $3,000 and saves $47.93 a month. The naive break-even is 63 months; discounted at 4 percent it is 71. And the number that decides it is not either of those — it is how long you keep the loan.