Housing tool
Mortgage Overpayment Calculator UK
Estimate how much interest you could save and how much sooner you could clear your mortgage by making regular monthly overpayments or a one-off lump sum.
Important note
Many mortgage deals have annual overpayment limits, often around 10% of the balance, but this varies by lender and product. Always check your own mortgage terms before making overpayments.
Interest saved
£32,680
Estimated reduction in total interest.
Time saved
4 years 7 months
Estimated time cut from your mortgage term.
Overpayment summary
Strong impact
Regular payment: £1,261/month
This overpayment plan could make a strong difference to both the total interest paid and the time left on the mortgage.
Without overpayments
25 years
Interest: £158,178
With overpayments
20 years 5 months
Interest: £125,498
Overpayment allowance check
Planned annual overpayment
£1,800
Monthly overpayments plus any one-off overpayment entered.
Example 10% allowance
£22,000
A rough reference only. Your actual allowance may differ.
Allowance position
£20,200 remaining
Your lender may use different rules or charge early repayment fees.
What this means
Mortgage overpayments can be powerful because they reduce the balance that future interest is charged on. The earlier and more consistently you overpay, the more noticeable the effect can become.
How mortgage overpayments work
A mortgage overpayment is an extra payment made on top of your normal monthly mortgage payment. Because it reduces the remaining balance, less interest may build in future months.
Regular monthly overpayments can be easier to budget for, while a one-off lump sum can have an immediate effect on the balance. The earlier an overpayment is made, the longer it has to reduce future interest.
This calculator gives a general estimate only. Your actual savings may vary depending on your lender, mortgage product, interest calculation, overpayment rules and any early repayment charges.
Monthly overpayments
Extra regular payments can gradually reduce your balance and interest.
Lump sums
A one-off overpayment can reduce the balance immediately.
Allowance limits
Many mortgage products limit how much you can overpay without charges.
How to use this result
Use the interest saved and time saved figures to judge whether overpaying feels worthwhile compared with other goals like emergency savings, debt repayment, or investing.
Overpayments can be especially effective when rates are higher, but always check whether your mortgage has overpayment limits or early repayment charges.
This calculator gives an estimate only and does not replace personalised mortgage advice.
Mortgage overpayment calculator FAQs
Is it worth overpaying my mortgage?
It can be, especially if it reduces interest and shortens the term, but it depends on your mortgage rate, savings needs, and any overpayment charges.
What is a common overpayment limit?
Many deals allow around 10% of the balance per year without a charge, but the exact rule depends on your lender and product.
Should I overpay monthly or make a lump sum?
Both can help. Earlier overpayments usually reduce interest sooner, but you should keep enough cash for emergencies.
Is this calculator mortgage advice?
No. This calculator gives a general estimate only and should not be treated as mortgage advice.
Next step
Compare overpayments with your wider plan
A useful next step is checking your monthly budget, emergency savings target, or overall mortgage affordability.
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Monthly Budget Planner
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Emergency Fund Calculator
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Important
This tool provides general estimates and educational guidance only. It does not account for your full personal circumstances and should not be treated as financial advice or a personal recommendation.