UK Money Tools Mortgage Repayment Calculator
See your payments, remaining balance and the difference overpayments could make.
Step 1
Your figures
Enter your details below. Your estimate updates automatically.
Step 2
Your estimate
Initial regular monthly payment
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Regular monthly payment after the fixed deal
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Interest saved versus no overpayments
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See the breakdown
Total interest with overpayments
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Total cost including capital due at the end
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Total extra payments applied
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Capital still due at the end
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Months saved
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Schedule length in months
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How it is calculated
Regular payments exclude extras. The follow-on payment uses the balance after your overpayments and the original remaining term. Total cost includes any interest-only capital still due.
Mortgage balance over time
Annual balance table
| Time | No overpayments | Your overpayments |
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About this calculator
See your payments, remaining balance and the difference overpayments could make.
Assumptions and limits
This is a monthly estimate using annual rate divided by 12. It assumes month-end payments, no missed payments, and a constant variable rate after any fixed deal. Lenders may calculate daily interest and round payments differently. Overpayments reduce the term during each repayment rate period; lenders may instead reduce your monthly payment.
Worked example
A £200,000 repayment mortgage over 25 years at a constant 5% annual rate is approximately £1,169.18 a month. With no fees or overpayments, the model estimates about £150,754.02 interest and £350,754.02 paid in total. This illustrates the calculation and is not a live mortgage quote.
Assumptions and exclusions
Fees, insurance, early repayment charges, offset accounts, part-and-part mortgages and affordability assessments are excluded. Check your lender’s overpayment allowance and deal terms before acting. This is a planning estimate, not a mortgage offer or advice.
Frequently asked questions
Is the variable rate a live market rate?
No. Enter the current rate quoted by your lender or a rate you want to test. The calculator holds this rate constant for the projection; it does not predict future rates.
Do interest-only payments repay the mortgage?
Regular interest-only payments cover interest. Only the overpayments entered here reduce capital. Any remaining capital must be repaid separately at the end of the mortgage term.
Can I overpay without a charge?
Check your mortgage offer. Allowances, annual reset dates and early repayment charges vary by lender and product. This calculator excludes charges and does not assume a universal 10% allowance.
How are monthly mortgage payments estimated?
The model divides the annual interest rate by 12 and calculates a monthly schedule with month-end payments. Repayment payments cover interest and capital; interest-only payments cover interest. Daily interest calculations and lender rounding can produce different figures.
What happens when the fixed deal ends?
The calculator uses the follow-on rate you enter and the remaining mortgage balance and term. It holds that rate constant for the projection. Use different rates to compare scenarios rather than treating the projection as a forecast.
How does the mortgage term affect repayments?
With the same balance and rate, a longer repayment term usually lowers the monthly payment but increases the total interest paid. A shorter term usually raises the monthly payment and reduces total interest.
Are mortgage fees included in the results?
No. The calculation uses the mortgage balance, rates, term and overpayments you enter. Product fees, valuation costs, insurance and early repayment charges are excluded unless you have already included a fee in the mortgage balance.