Mortgage balance over time
Standard repayment path compared with your overpayment scenario.
StandardWith overpayments
Mortgage Repayment Calculator
Estimate monthly mortgage repayments, total interest, and the impact of regular overpayments.
Monthly repayment£1,604Before voluntary overpayments
Interest saved£34,279Against the standard mortgage path
Time saved3 years 9 months
Mortgage breakdown
Loan amount80.0% LTV£280,000
Standard total interest£201,317
Overpayment total interest£167,039
Estimated payoff21 years 3 months
Assumptions
Calculation notes
- Uses constant-rate repayment mortgage maths with monthly compounding.
- Does not include lender fees, rate changes, early repayment charges, product fees, or overpayment caps.
- This is an estimate for planning, not mortgage advice.
Repayment path
How the mortgage schedule is estimated
The mortgage result is an amortisation scenario: each payment is split between interest and reducing the balance.
Amortisation method
The repayment calculation uses standard amortisation maths from loan amount, interest rate and term.
Optional overpayments reduce the outstanding balance earlier, which can reduce total interest and shorten the repayment path in the estimate.
Repayment flowloan balance, interest rate and term -> monthly repayment schedule; optional overpayment -> faster principal reduction
Overpayment scenario
Example: GBP 300,000 mortgage with GBP 200 overpayment
- Loan amount: GBP 300,000
- Interest rate: selected by user
- Term: selected by user
- Monthly overpayment: GBP 200
Result: The overpayment scenario is compared with the standard repayment path for interest and payoff timing.
Overpayments usually help most when they reduce principal early, but lender limits and charges still matter.
Interest, term and overpayments
- A constant-rate model is useful for comparison but cannot know future remortgage rates.
- Check annual overpayment allowances, early repayment charges and whether the lender reduces the term or future monthly payment.
Content reviewed: 7 September 2026.
Guide
Mortgage Repayment Calculator notes
Model a repayment mortgage with deposit, interest rate, term, and optional overpayments to compare cost and payoff timing.
Review the calculation notes where rules, tax years, thresholds, or eligibility affect the result.
FAQs
Mortgage Repayment Calculator FAQs
What is the Mortgage Repayment Calculator for?
Model a repayment mortgage with deposit, interest rate, term, and optional overpayments to compare cost and payoff timing.