Mortgage Calculator
Calculate monthly mortgage payments, total interest, and affordability based on property price, deposit, interest rate, and term length.
Last updated: March 2026
Monthly Payment
£$1,250.62
Total Repayment
£$375,187
Total Interest
£$150,187
Loan-to-Value
90.0%
How You Compare
Your mortgage rate is better than 50% of UK residential mortgages.
Industry typical: 3.5-6.0%
Source: Bank of England 2025
💡 What This Means
- 📊 £1251/month is a typical UK mortgage payment. Budget an additional 1-2% of the property value per year for maintenance.
- 💰 You'll pay £150187 in interest — that's 40% of total repayment. Overpaying by even £100/month could save you thousands.
- ⚠️ Your LTV of 90.0% is high. Aim for under 80% to access the best interest rates — even a small increase in your deposit helps.
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What is Mortgage Repayment?
A mortgage repayment is the monthly amount you pay to your lender covering both the interest on your loan and a portion of the principal. Understanding your monthly commitment is essential before committing to a property purchase. Use the Home Affordability Calculator to check what you can borrow, and the Stamp Duty Calculator to estimate upfront tax costs.
The Formula
Monthly Payment = P × [r(1+r)^n] ÷ [(1+r)^n − 1]
P = principal (loan amount), r = monthly interest rate (annual rate ÷ 12), n = total number of monthly payments (term in years × 12).
Worked Example
A £250,000 property with a £50,000 deposit gives a £200,000 mortgage at 4.5% over 25 years.
- Principal (P) = £200,000
- Monthly rate (r) = 4.5% ÷ 12 = 0.375% = 0.00375
- Number of payments (n) = 25 × 12 = 300
- Monthly Payment = £200,000 × [0.00375 × 1.00375^300] ÷ [1.00375^300 − 1] = £1,111
- Total repaid = £1,111 × 300 = £333,300. Total interest = £133,300
📌 Monthly repayments of £1,111 over 25 years, with £133,300 in total interest — 67% of the original loan amount.
Why This Matters
Affordability stress test
Lenders stress-test at current rate + 3%. If your mortgage is at 4.5%, you must afford payments at 7.5%. Calculate both scenarios to understand your true affordability buffer before making an offer.
Term length trade-off
A 30-year term reduces monthly payments by ~15% vs 25 years, but increases total interest by 30-40%. Use the calculator to model different terms and find your optimal balance between monthly comfort and total cost.
Common Mistakes
❌ Forgetting additional costs
Your monthly housing cost includes mortgage payment, buildings insurance, service charge (flats), ground rent (leasehold), and maintenance. Budget an extra 20-30% on top of the mortgage payment for these.
❌ Not modelling rate changes
Fixed rates end after 2-5 years. If you fix at 4.5% but the variable rate is 6.5% when your fix ends, your payments jump from £1,111 to £1,320/month. Always model the worst-case scenario.
Industry Benchmarks
| Category | Good | Average | Poor |
|---|---|---|---|
| Monthly payment as % of income | Below 28% | 28-36% | Above 36% |
| Total interest over term | Below 60% of principal | 60-100% | Above 100% |
Related Tools
Home Affordability Calculator
Estimate how much home you can afford based on your income, deposit, debts, and monthly expenses. See your maximum property price and mortgage amount.
Use free →Real EstateStamp Duty Calculator
Calculate UK stamp duty land tax on property purchases. See rates for first-time buyers, additional properties, and the total tax due on your purchase price.
Use free →Real EstateRental Yield Calculator
Calculate rental yield on investment properties.
Use free →Real EstateBuy vs Rent Calculator
Compare costs of buying vs renting a home.
Use free →Frequently Asked Questions
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