How to Use the Mortgage Calculator

Enter the property price, your deposit amount, the interest rate offered by your lender, and the mortgage term in years. The calculator will instantly show your monthly repayment, total interest paid, and the overall cost of the mortgage.

Repayment vs Interest-Only

A repayment mortgage means every monthly payment reduces the capital you owe, so the balance reaches zero at the end of the term. An interest-only mortgage means your payments only cover the interest — the full original loan remains at the end and must be repaid separately.

Loan-to-Value (LTV)

Your LTV is the loan amount as a percentage of the property price. Most lenders offer better rates at lower LTVs — typically 60%, 75%, and 85% are the key thresholds. A 20% deposit gives you an 80% LTV.

Frequently Asked Questions

How is a monthly mortgage payment calculated?

For a repayment mortgage, the formula is M = P[r(1+r)^n] / [(1+r)^n - 1], where P is the loan, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments.

What deposit do I need to buy a house in the UK?

Most UK lenders require a minimum of 5–10% deposit. However, a 20–25% deposit will unlock significantly better interest rates, reducing the total cost of your mortgage considerably.

Does the calculator include stamp duty?

No — this calculator focuses on mortgage repayments. Stamp duty is a separate one-off cost paid on completion. Use the government's stamp duty calculator for an accurate figure based on your situation.