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UK Mortgage Calculator

Work out your monthly mortgage payment, total interest and loan-to-value for a repayment or interest-only mortgage.

Your mortgage

£
£
%
25 years
Monthly payment (repayment) for 25 years LTV —
£—
Loan amount£—
Total interest paid£—
Total repaid£—
Remaining balance
Show yearly breakdown
YearBalancePrincipal paidInterest paid

This is a standard amortisation calculation with no UK-specific thresholds. Interest rates are assumptions you enter — current rates vary by lender and product. See Bank of England for the official Bank Rate. Your actual payment depends on the product and fees.

How it works

Enter the property price, your deposit and the mortgage term, choose a repayment or interest-only mortgage, and set an assumed annual interest rate. The calculator shows your monthly payment, the loan amount (price − deposit), your loan-to-value (LTV), and how much interest you would pay over the full term. For a repayment mortgage it also shows how the balance falls each year.

Example calculation

For a £300,000 property with a £60,000 deposit (loan £240,000) at 5% over 25 years:

  • Monthly payment (repayment): ≈ £1,403
  • Loan-to-value: 80%
  • Total repaid: ≈ £420,905
  • Total interest: ≈ £180,905

Example assumes a fixed 5% rate for the whole term with no fees. Most UK mortgages fix for 2–5 years, then move to the lender's standard variable rate — your actual cost will differ.

Methodology & formula

For a repayment mortgage, the monthly payment uses the standard annuity formula:

M = P × r(1 + r)n / [ (1 + r)n − 1 ]
  • P = loan amount (property price − deposit)
  • r = monthly interest rate = annual rate ÷ 12
  • n = number of monthly payments = term × 12

Total interest = (monthly payment × n) − P. For an interest-only mortgage, the monthly payment is simply P × r (interest only), and the loan is repaid separately at the end. LTV = loan ÷ property price.

Assumptions: constant interest rate for the whole term, no arrangement or other fees, no overpayments, monthly payments. Real rates move — a rate change can substantially change your payment.

UK-specific information

  • Repayment vs interest-only: Most UK mortgages are repayment, so the loan is cleared by the end of the term. Interest-only is common for buy-to-let and requires a separate repayment vehicle.
  • Fixed vs variable: UK mortgages typically fix for 2, 3 or 5 years, then revert to the lender's Standard Variable Rate (SVR). Tracker mortgages follow the Bank of England Bank Rate.
  • LTV matters: A lower loan-to-value (bigger deposit) usually unlocks lower interest rates. Products are commonly banded at 60%, 75%, 80%, 85% and 90% LTV.
  • Stamp Duty: buying a home in England or Northern Ireland may mean paying Stamp Duty Land Tax on the purchase price — separate from the mortgage. GOV.UK · 2026/27

Market context as at 2026 — the Bank of England Bank Rate and lender rates change frequently; this calculator uses the rate you enter.

Frequently asked questions

How much can I borrow for a UK mortgage?
Most UK lenders offer roughly 4–4.5 times your annual income, sometimes more, and stress-test payments against higher interest rates. This calculator shows monthly payments, not how much you can borrow.
What is a good deposit to save?
A 20% deposit (80% LTV) is a common target — it usually opens up lower rates than a 10% deposit. Under the Help to Buy equity loan you need at least 5%.
Repayment or interest-only — which should I choose?
Repayment mortgages pay off the loan automatically and are the standard choice for a home you plan to keep. Interest-only suits borrowers with a separate investment or pension plan to repay the capital.
Does the calculator include fees?
No. Arrangement fees, valuation fees and legal costs are separate. A slightly higher-rate product with a lower fee can sometimes be cheaper overall.
What happens when my fixed rate ends?
You normally move to the lender's standard variable rate, which is often higher. Many people remortgage to a new fixed deal before the existing one ends.
Can I make overpayments?
Yes, many UK mortgages allow overpayments up to 10% of the balance each year without penalty. Overpaying reduces interest and the term — see the Mortgage Overpayment calculator when it launches.

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Sources

Casvia provides educational calculators and general information. It does not provide personal financial, tax or investment advice. Interest rates and products change — always check the latest official guidance.