Early mortgage repayment calculator
Find out how much an overpayment on your mortgage could save, and whether shortening the term or lowering the payment serves you better.
What happens when you repay part of a mortgage early?
An overpayment is a one-off payment on top of the regular instalment. It goes entirely on the principal, so it reduces what you owe directly. Since interest is always charged on the balance, a smaller debt means less interest every month that follows.
Think of it as cutting a slice off the debt. Interest is always calculated on the balance so when the balance falls, so does the interest in every single month that follows, right to the end. That is exactly why an overpayment does more the sooner you make it.
From there the usual amortisation continues: the month's interest is the balance times the monthly rate, and the rest of the payment comes off the principal.
| Symbol | Name | Jednotka |
|---|---|---|
| Monthly payment | € | |
| Outstanding balance | € | |
| Overpayment | € | |
| Monthly interest rate | ||
| Remaining instalments |
Two things you can do with the smaller debt
After an overpayment the bank asks what should change. Mathematically it is the same reduced principal either way: only how you spread it over time differs.
- Cut the term
- The monthly payment stays roughly the same, but the loan ends sooner. Because the debt disappears faster, there is less time for interest to accrue, so this saves the most.
- Cut the payment
- The end date stays where it was and the monthly payment falls. You save less interest, but more stays in your budget every month.
If the aim is to pay as little as possible, cut the term. If you need to free up the monthly budget, after a drop in income, say, or a rise in other costs, cutting the payment makes sense.
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Terms that come up in this calculation
- MortgageA long-term loan secured on a property. The bank lends most of the purchase price and the debt is repaid in regular instalments, usually over 20 to 30 years.
- AnnuityA series of regular payments of the same size at equal intervals. On a loan it is the instalment that never changes for the whole of the repayment.
- Interest rateThe price of borrowed money expressed as a percentage per year. It says how much extra you pay if you borrow or how much extra you receive if you are the one lending.
- RefinancingMoving an existing loan to another bank on better terms. The new loan pays off the old one and from then on you repay only the new bank.
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