Mortgage Overpayment Calculator
100% in your browser — nothing is uploadedApplied straight to principal, on top of your scheduled payment
Interest you'd save
$105,429
Paid off 6 yr 7 mo sooner
Assumes the extra goes entirely to principal and your rate is fixed. Check that your servicer applies extra payments to principal, not next month's bill.
Paying a little extra toward your mortgage principal each month is one of the highest-guaranteed-return moves in personal finance — every dollar saves you that loan's interest rate, tax-free. This calculator shows exactly what a given extra payment does: how many years it cuts off the loan and how many thousands of dollars of interest it saves.
The effect is larger than most people expect because early extra payments attack the balance while interest is compounding hardest. Even $100–$200 a month can shave years off a 30-year loan. Enter your numbers and watch the interest-saved figure — it's usually the most motivating number in your whole budget.
How to use the mortgage overpayment calculator
- Enter your current loan balance, interest rate, and years remaining.
- Enter the extra amount you'd add to each monthly payment.
- Read the interest saved and how much sooner you'd be mortgage-free.
Frequently asked questions
How does paying extra save so much interest?
Extra payments go straight to principal, so you stop paying interest on that money for the rest of the loan. Early in a mortgage most of your scheduled payment is interest, so reducing the balance now has an outsized effect compounded over the remaining years.
Is overpaying my mortgage better than investing?
It's a guaranteed, risk-free return equal to your mortgage rate. If your rate is high (say 6–7%), that's hard to beat safely. If it's low and markets may return more, investing could win — but overpaying is certain, and certainty has value.
Will my lender apply extra payments correctly?
Usually yes, but confirm the extra is applied to principal — some servicers default to 'paying ahead' on next month's bill instead, which doesn't save interest. Many let you specify 'principal only' online.
Is anything I enter uploaded?
No — the calculation runs entirely in your browser and nothing is stored or sent.