⚡ Mortgage Overpayment Calculator
See how much time and interest you save by making extra monthly payments or a one-off lump sum on your mortgage.
Enter your values
- Years saved7.58
- Total interest saved€64,925.12
- Standard total interest€223,813.88
- With overpayment total interest€158,888.76
What this means
- Overpaying saves 91 months off your mortgage term.
- Total interest saved: €64,925.12.
- Standard schedule total interest: €223,813.88.
- With overpayments total interest: €158,888.76.
Visual results
Detailed breakdown
| Year | Standard schedule | With overpayment |
|---|---|---|
| 1 | €236,459.12 | €234,003.35 |
| 2 | €232,737.09 | €227,699.90 |
| 3 | €228,824.63 | €221,073.96 |
| 4 | €224,712.00 | €214,109.02 |
| 5 | €220,388.96 | €206,787.74 |
| 6 | €215,844.74 | €199,091.89 |
| 7 | €211,068.04 | €191,002.31 |
| 8 | €206,046.95 | €182,498.84 |
| 9 | €200,768.97 | €173,560.33 |
| 10 | €195,220.95 | €164,164.50 |
About this calculator
Why overpaying your mortgage matters
On a standard 30-year mortgage, the total interest you pay often exceeds the original loan amount. Extra payments — even small ones — cut both the time you carry the debt and the interest it generates, because every euro of extra principal paid now never accrues future interest.
How amortization works against you early on
In the early years of a mortgage, the monthly payment is mostly interest. On a €240,000 loan at 5%, the first payment is roughly €1,288 — about €1,000 of that is interest and only €288 reduces the balance. This ratio gradually shifts over time. Overpaying in the early years is particularly powerful because you skip many future high-interest months.
Extra monthly payments vs lump sums
Both approaches work, but they differ in flexibility and timing:
- Extra monthly payments are predictable and discipline-forming. Even €100–200 extra per month can save 3–5 years on a typical 30-year mortgage.
- Lump sum payments (a bonus, inheritance, or savings windfall) are most impactful when applied early and directly to principal. The earlier in the loan, the greater the compounding benefit.
Many borrowers combine both: a small fixed overpayment each month, with occasional larger lump sums when cash is available.
Things to check before overpaying
- Early repayment charges (ERCs): some lenders charge a fee for overpaying above a threshold (often 10% per year). Check your mortgage terms.
- Offset mortgages: if you have an offset or current-account mortgage, keeping savings in the linked account may achieve a similar interest-reduction effect without formal overpayment.
- Emergency fund first: before directing extra cash to the mortgage, ensure you have 3–6 months of expenses in liquid savings.
Frequently asked questions
How does extra monthly payment reduce my mortgage term?
Every extra euro you pay goes directly to reducing the principal balance. A lower principal means less interest accrues the following month, so more of your regular payment then also goes to principal — a compounding effect. Even modest extra payments applied consistently can cut years off a 30-year mortgage and save tens of thousands in interest.
When is the best time to apply a lump sum?
Earlier is almost always better. A lump sum in month 1 reduces the balance on which all subsequent interest is calculated, maximising interest savings. The same lump sum applied in year 20 of a 30-year mortgage saves far less because most of the interest has already been paid and the remaining balance is much smaller.
Should I overpay my mortgage or invest the money instead?
It depends on the effective after-tax interest rate versus the expected investment return. If your mortgage rate is 5% and you expect a 7% investment return, investing may yield more — but with higher risk. Overpaying the mortgage is a guaranteed risk-free return equal to your mortgage rate. Many people choose a mix: overpay enough to pay off comfortably, invest the rest for growth.