Mortgage Overpayment Calculator
Enter your balance, rate and remaining term, then add a monthly overpayment, a lump sum or both. See the interest saved and how much sooner you finish.
Este contenido está en inglés.
These figures are estimates only and are not advice. This is for a repayment mortgage at a single fixed rate, with interest worked out monthly. Lenders often limit overpayments on a fixed deal, for example to 10% of the balance each year, and may charge for going over. Check your own terms.
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Ejemplos resueltos
Overpaying £200 a month
Balance £200,000, rate 4.5 per cent, 25 years remaining, overpayment £200 a month
The mortgage is cleared in 227 months (18 years and 11 months) instead of 300, saving £36,280.39 in interest.
Each extra pound reduces the balance straight away, so less interest builds up in every later month.
Lump sum early in the term
Balance £200,000, rate 4.5 per cent, 25 years remaining, lump sum £10,000 in month 0
The mortgage is cleared in 274 months (22 years and 10 months), with total interest of £114,199.03.
The lump sum is taken off the balance at the start, which is why it saves more interest than the same amount repaid later.
Sobre Mortgage Overpayment Calculator
This mortgage overpayment calculator shows what happens when you pay more than your required monthly amount. Enter your balance, interest rate and remaining term, then add a monthly overpayment, a one-off lump sum or both. It compares your mortgage with and without the extra payments and shows the interest saved and the time cut from your term. Results update as you type, so you can test different amounts and compare them side by side, from a modest monthly sum to a large one-off payment.
The lump sum can go in straight away or after a number of months, so you can model a bonus, a gift or a planned saving. The comparison table lists the monthly payment, the time to pay off, the total interest and the total you repay in each case. It is a quick way to judge whether a small regular overpayment, a larger lump sum or a mix of the two is the better use of spare money. The total to repay shows the full cost of the loan in each case.
Cómo usar Mortgage Overpayment Calculator
- Enter your mortgage balance, interest rate and the years and months remaining.
- Add an extra monthly amount, a lump sum, or both.
- If the lump sum comes later, enter how many months from now it will go in.
- Compare interest and time saved, and the table with and without overpaying.
Usos habituales
- Deciding whether to overpay or save instead
- Planning what to do with a bonus or inheritance
- Seeing how much a small monthly overpayment helps
- Preparing questions for your lender about overpayment limits
Fuentes
- Mortgage overpayments (MoneyHelper, the government backed money guidance service)
- Tax on savings interest (GOV.UK)
Última revisión: 15 de octubre de 2026.
Preguntas frecuentes
How do overpayments save interest?
Each overpayment reduces the balance straight away, so less interest builds up in every later month. The saving grows over time because the lower balance also means smaller interest charges each month for the rest of the term, shortening the time it takes to clear the loan.
Is a lump sum or a monthly overpayment better?
A lump sum made early usually saves more than the same total spread over small amounts, because it cuts the balance sooner. Monthly overpayments are easier to afford and still add up. You can enter both and compare the interest saved.
Will my lender let me overpay?
Many lenders allow a set amount each year, often around 10% of the balance on a fixed deal, without a charge, and may charge a percentage for going over. Check your mortgage terms or ask your lender before you make an overpayment.
Does this work for interest-only mortgages?
No. It assumes a repayment mortgage at one rate for the rest of the term. Interest-only loans work differently because the monthly payment only covers interest, so overpayments reduce the balance owed at the end rather than the term.
Why might my lender's figures be different?
Interest on a real mortgage is often worked out daily, rates change, and lenders have their own rules about when an overpayment takes effect. This tool works out interest monthly at one twelfth of the annual rate. It is an estimate only and is not advice.