UK Mortgage Repayment Calculator

What the mortgage repayment calculator does

The calculator turns how much you borrow, the interest rate and the length of the mortgage into your monthly payment. It also shows the total you will repay over the term and how much of that is interest.

A mortgage is usually a household’s largest commitment, and the monthly payment shapes the budget for decades. Seeing it before you commit lets you check it fits your income, and comparing scenarios shows how the rate and term pull the cost in different directions.

How a repayment mortgage works

Each month you pay the interest on the outstanding balance plus part of the balance itself. Early on most of the payment is interest, because the balance is large; as the balance shrinks, more of each payment reduces the loan, until the final payment clears it.

That is why the payment stays level on a fixed rate even though the split between interest and capital changes. The calculator uses the standard formula that produces this level payment.

For example, £250,000 over 25 years at 5% costs about £1,461.48 a month. Over 300 months you repay about £438,444, of which about £188,444 is interest.

The role of the interest rate

The rate has a large effect on the total cost. Because a mortgage runs for so long, a difference of half a per cent changes the monthly payment noticeably and can add or save many thousands of pounds of interest over the term.

UK mortgages often start with a fixed or discounted rate for two, three or five years before moving to the lender’s standard variable rate. The calculator assumes one rate for the whole term, which is ideal for comparing deals like for like. When your fixed period ends, recalculate with the new rate or with a remortgage rate you are considering.

The role of the term

The term is usually somewhere between about ten and forty years. A longer term spreads the debt over more payments, so each is smaller, but you pay interest for longer and the total interest is higher. A shorter term means larger payments but clears the debt sooner with much less interest. Which is right depends on what your income can support; trying two terms makes the trade-off clear.

How the calculation works

• It converts the annual interest rate into a monthly rate.
• It counts the number of monthly payments in the term.
• It applies the repayment formula to find the level payment that clears the balance by the final month.
• It multiplies that payment by the number of months for the total repaid and subtracts the loan to give the total interest.

What you need to enter

• The loan amount: the property price minus your deposit.
• The annual interest rate on the deal you are considering.
• The mortgage term in years.

If you are still shopping around, use a lender’s or broker’s quoted rate. A larger deposit can move you into a lower loan-to-value band with a better rate. Regular overpayments would clear the balance faster and cut the interest below the figure shown.

Reading your result

The output shows the monthly payment, the total paid over the term and the total interest. The monthly payment is the budgeting figure; the total interest is the cost of borrowing, and seeing it in pounds rather than as a rate often changes how a mortgage feels.

Real mortgages carry extras the calculator does not model, such as arrangement or product fees, valuation costs and rate changes when a fixed period ends. Check a lender’s illustration for the exact figures, including fees, before you commit.

When to use this tool

• To estimate the monthly cost of a mortgage before you apply.
• To compare two interest rates or two terms on the same loan.
• To see how much interest a longer term adds.
• To check a payment fits comfortably within your budget.

Recalculate whenever you remortgage or consider a new deal.

This is general information only and not financial advice.

About This Mortgage Repayment Calculator

Use this mortgage repayment calculator to get an instant estimate based on the figures you enter. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.