Calculator
Mortgage Calculator
Estimate your monthly mortgage payment, total interest paid, and the full repayment schedule. Adjust the inputs to see results update instantly.
UK / US / EU: Switch currency in the top-right to convert symbols and unlock region-specific helpers. Selecting USD reveals a US state preset that pre-fills annual property tax at the state's average effective rate — a much bigger line item in the US than in the UK, and one most online calculators ignore.
Loan details
10% of property price
Pre-fills annual property tax using the state's average effective rate.
Capital vs interest
How the mortgage calculator works
This calculator works out your monthly mortgage payment from four numbers: the property price, your deposit (or down payment), the annual interest rate, and the term in years. The loan principal is simply price − deposit, and from there we apply the standard amortisation formula used by UK and US lenders.
The formula
For a repayment (capital + interest) mortgage:
M = P × [r(1+r)^n] / [(1+r)^n − 1]
- M — monthly payment
- P — loan principal (price minus deposit)
- r — monthly interest rate (annual rate ÷ 12)
- n — total number of monthly payments (years × 12)
For an interest-only mortgage the monthly payment is just P × r, and the full principal is repayable at the end of the term. Property tax and home insurance, where supplied, are divided by 12 and added on top to give a full PITI figure (Principal, Interest, Tax, Insurance).
Worked example
Scenario: £350,000 home, £50,000 deposit, 4.75% rate, 25-year repayment.
Loan principal: £350,000 − £50,000 = £300,000
Monthly rate (r): 4.75% ÷ 12 = 0.003958
Number of payments (n): 25 × 12 = 300
Monthly payment: £1,710.50
Total repaid over 25 years: £513,151 — of which £213,151 is interest.
Frequently asked questions
How is a monthly mortgage payment calculated?
The standard amortisation formula is M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the loan principal (price minus deposit), r is the monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments (years × 12). Property tax and home insurance are added on top to give a full PITI figure.
What is the difference between repayment and interest-only mortgages?
On a repayment mortgage you pay both capital and interest each month, so the loan is fully cleared by the end of the term. On interest-only you pay just the interest, leaving the original loan balance to be repaid as a lump sum at the end — usually from savings, investments, or selling the property. Interest-only payments are lower month-to-month but cost far more in total interest.
Does the calculator include UK stamp duty or US closing costs?
Stamp duty and closing costs are one-off purchase costs, not part of the monthly mortgage payment, so they are not included here. Use our separate Stamp Duty calculator for UK figures. The US-state preset on this page does pre-fill annual property tax based on each state's average effective rate.
How does loan-to-value (LTV) affect my mortgage?
LTV is the loan amount divided by the property price. A lower LTV (i.e. a larger deposit) typically unlocks better interest rate tiers — UK lenders price differently at 60%, 75%, 80%, 85%, 90% and 95% LTV. In the US, LTVs above 80% on conventional loans usually require Private Mortgage Insurance (PMI), which adds to the monthly cost.
Are the figures accurate enough to apply for a mortgage?
The math is exact for the inputs you give, but real mortgage offers depend on your credit profile, lender fees, the specific product rate, and items like PMI, HOA, or service charges that this calculator does not model. Treat the result as a planning estimate, not a quotation.
Why does my interest paid seem so high compared to the loan amount?
On a 25–30 year term, total interest can rival or exceed the loan principal — especially at higher rates — because interest compounds across hundreds of payments. Shortening the term, overpaying, or refinancing onto a lower rate are the three main levers to reduce total interest paid. Try halving the term in this calculator to see the dramatic effect.