Calculate Your UK Mortgage Repayments Instantly
Use our free UK Mortgage Calculator to estimate your monthly mortgage repayments, total interest payable, loan amount and overall borrowing costs. Simply enter your property price, deposit, mortgage interest rate and repayment term to see instant results.
Whether you’re a first-time buyer, moving home or remortgaging, this calculator helps you understand what your monthly payments could look like before applying for a mortgage
How mortgage repayments work
Every repayment mortgage payment has two parts. The capital part pays down the amount you borrowed. The interest part is the lender’s charge for the loan, worked out each month on the balance you still owe.
In the early years, when the balance is large, most of each payment is interest. As the balance shrinks, the interest part shrinks with it, so more of each payment goes toward capital and the balance falls faster in the later years. This shift is automatic on a standard repayment mortgage.
If your rate is fixed, your monthly payment stays the same through the fixed period even as the split between capital and interest changes underneath it. On a variable or tracker rate, the payment can go up or down when the rate changes.
Calculate your monthly mortgage repayments instantly.
Estimate your monthly payment, total interest, loan amount, and borrowing costs using clear UK mortgage assumptions.
Amortization Schedule
| Month | Payment | Principal | Interest | Balance |
|---|
Repayment Breakdown
Mortgage Rate Comparison
See how a different interest rate changes the monthly payment, interest paid and total cost over the same 34-year term.
| Rate | Monthly | Interest | Total |
|---|---|---|---|
| 3% | £1,012 | £124,000 | £364,000 |
| 4% | £1,180 | £186,000 | £426,000 |
| 5% | £1,348 | £245,000 | £485,000 |
| 6% | £1,528 | £310,000 | £550,000 |
Need More UK Mortgage Tools?
Explore our free calculators to compare costs, understand affordability and plan your next move.
- Mortgage Overpayment Calculator
- Stamp Duty Calculator
- Buy-to-Let Calculator
- Remortgage Calculator
- Lifetime ISA Calculator
- Savings Calculator
How Mortgages Work in the UK
Most UK homebuyers use a repayment mortgage, which means each month you pay part of the capital balance and part of the interest. Over time, the balance falls and the interest portion decreases. Understanding the structure of a mortgage helps you compare lenders and decide whether a fixed or variable deal is better for your circumstances.
How to Use This Calculator
Enter your property price, deposit, interest rate, mortgage term and monthly income to get a realistic monthly estimate. The calculator updates instantly so you can compare scenarios before speaking to a lender or broker. It is especially useful if you want to understand how a larger deposit or a lower rate could affect your monthly commitment.
Fixed vs Variable Rates
A fixed-rate mortgage locks your interest rate for a set period, usually two, three or five years. That gives certainty over monthly payments. A variable-rate mortgage follows the lender’s standard variable rate or a tracker rate linked to the Bank of England base rate, so payments can move up or down. For many borrowers, a fixed rate offers peace of mind, while a variable deal may offer a lower initial rate.
Mortgage Affordability Explained
Lenders assess affordability by reviewing income, regular outgoings, credit history and the size of your deposit. They usually test whether the mortgage payment would remain affordable if rates rose. This is why a larger deposit, lower loan size and stable income can make a big difference to your borrowing options.
What is APR?
APR stands for Annual Percentage Rate and is used to show the overall cost of borrowing, including the interest rate and certain fees. For mortgage comparison, it can be useful, but many homeowners focus on the rate, the mortgage term and the total repayment because fees and incentives vary widely between lenders.
How Lenders Assess Affordability
Most lenders look at your salary, bonus income, regular expenditure and any debts. They may also evaluate your credit score, past missed payments and the size of the deposit relative to the purchase price. A strong affordability profile can help you access better rates and larger borrowing amounts.
Stamp Duty Overview
Stamp Duty Land Tax (SDLT) is a tax payable when buying property in England and Northern Ireland. The amount depends on the purchase price and whether you are a first-time buyer. In Scotland and Wales the equivalent taxes are LBTT and LTT. For many buyers, stamp duty is a significant upfront cost and should be included in any overall home-buying budget.
Should You Use a Mortgage Repayment Calculator?
A mortgage repayment calculator is useful before you make an offer, remortgage or compare deals. It helps you estimate how much the loan could cost each month and whether the payment leaves enough room in your budget for bills, childcare, travel and savings. It is not a substitute for advice from a mortgage broker or adviser, but it is a smart first step for planning.
Frequently Asked Questions
- How accurate is this calculator? It gives a reliable estimate using standard amortization assumptions, but lenders may apply different rates, fees and criteria.
- Can I use it for buy-to-let? This calculator is designed for standard residential mortgage planning rather than specialist buy-to-let calculations.
- What interest rate should I use? Use a realistic estimate based on current lender offers or a rate you expect to qualify for.
- Does it include fees? No, this calculator focuses on the mortgage repayment itself and does not include arrangement fees, valuation fees or insurance products.
- Is this calculator free? Yes, it is intended as a free planning tool for homeowners and buyers.
- What is LTV in a mortgage? Loan-to-value compares the size of the loan to the property price and can affect the rate you are offered.
- How does a larger deposit help? A larger deposit usually reduces the loan amount, lowers the monthly payment and can improve the rate available.
Worked example: £250,000 over 25 years at 4.5% (illustrative)
Here is how the calculator reaches its monthly payment figure. The standard repayment formula is: M = P × r × (1+r)n / ((1+r)n – 1), where P is the loan amount, r is the monthly interest rate and n is the number of monthly payments.
Step by step on a £250,000 loan over 25 years (300 months) at an illustrative fixed rate of 4.5%:
- Monthly rate: 0.045 / 12 = 0.00375
- Growth factor: 1.00375300 = 3.07482 (rounded)
- Monthly payment: 250,000 × 0.00375 × 3.07482 / (3.07482 – 1) = £1,389.58
- Total paid over 25 years: £1,389.58 × 300 = £416,874
- Total interest: £416,874 – £250,000 = £166,874
Look at the very first month: interest is £250,000 × 0.00375 = £937.50, so only £452.08 of that first £1,389.58 payment clears capital. Next month the lender charges interest on the slightly smaller balance, so the capital share grows. Repeat that 300 times and the balance reaches zero.
This is an illustrative rate for the example only, not a quote. Your actual rate depends on your deposit, credit profile and the deals available when you apply.
Overpayments explained
An overpayment is any amount you pay above your normal monthly payment. Unlike the standard payment, the whole overpayment goes straight toward the balance, so next month’s interest is worked out on a smaller number. That is why even small overpayments can take years off a mortgage.
On the example above, adding just £100 a month to the £1,389.58 payment clears the mortgage in 266 months (22 years 2 months), about 2 years 10 months early. Total interest falls from about £166,874 to about £145,004, saving around £21,871. Check this yourself with the calculator by shortening the term until the payment matches your planned payment plus the overpayment.
Before you overpay, check your lender’s rules. Most lenders let you overpay up to 10% of the outstanding balance each year with no penalty, but anything above that can trigger early repayment charges while you are in a fixed deal. Keep a cash emergency fund first: money put into a mortgage is hard to get back out.
Questions answered
Will my monthly payment stay the same?
Only while your rate is fixed. During a fixed deal the payment is locked. After that, or on a tracker or standard variable rate, the lender recalculates your payment whenever the rate changes.
What costs are not included in the calculator?
The calculator covers the mortgage itself. Council tax, buildings insurance, maintenance and, for leasehold flats, service charges and ground rent all sit on top. If you are buying a leasehold flat, use our Leasehold Cost Reconciler to line up two years of service charges, ground rent and other leasehold costs and spot errors or overcharges.
How much can I borrow?
As a rough guide, most UK lenders lend around 4 to 4.5 times your annual income, then apply detailed affordability checks on your spending, debts and credit record. The final offer always comes from the lender, never from a calculator.
Is this financial advice?
No. This page is general information to help you understand mortgage costs. It is not financial advice and does not replace advice from a qualified mortgage adviser.
General information, not financial advice.