A mortgage is typically the largest financial commitment most people make, and the numbers matter at every stage: before you buy, when you are deciding how much to borrow, and once you are in repayment and want to understand your options. These calculators are built around the specific questions people actually ask — not a single generic tool that tries to do everything at once. Pick the one that matches your question below.
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Work out your monthly payment
If you are at the start of the process — shopping for a mortgage or stress-testing affordability — these calculators tell you what a given loan will cost each month and in total over the term.
Plan ahead and manage overpayments
Once you have a mortgage, these calculators help you understand what you still owe, how your balance will change over time, and what paying more than the minimum would save you.
Compare your options
These calculators help you assess whether a product or borrowing level makes sense for your situation before committing.
Existing scheme holders
This calculator is for people who already hold a government equity loan, not for new buyers.
Frequently asked questions
What is the difference between a repayment and an interest-only mortgage?
With a repayment mortgage, each monthly payment covers both the interest and a slice of the capital, so the balance falls every month and the loan is cleared at the end of the term. With an interest-only mortgage, payments cover only the interest — the full capital remains outstanding and must be repaid separately, usually when the property is sold or remortgaged. Most residential mortgages in the UK are repayment mortgages.
How much can I save by overpaying?
Even small regular overpayments can cut years from your term and save a significant amount in total interest, because any extra payment reduces the capital on which future interest is charged. The earlier in the term you overpay, the bigger the compound effect. The overpayment calculator shows the exact interest saving and term reduction for your current balance, rate, and overpayment amount.
What LTV do I need for the best mortgage rates?
UK lenders generally price their best deals at 60% LTV (a 40% deposit or equity stake). Rate steps typically occur at 75%, 80%, 85%, 90%, and 95%. The exact thresholds and pricing vary between lenders — use the LTV calculator to see which tier you fall into, then speak to a broker for actual product comparisons.
Can I use these calculators when remortgaging?
Yes. The balance calculator estimates what you still owe before you switch deals. The LTV calculator gives you your current loan-to-value ratio based on your estimated property value, which determines which rate tiers you can access. The repayment and overpayment calculators work identically for a new deal on your remaining balance.
Do these calculators include stamp duty?
No. These calculators focus on mortgage loan costs only — monthly payments, interest charges, and balance over time. Stamp Duty Land Tax (SDLT) is a separate purchase cost that depends on purchase price, buyer status, and property location. It is not included in any of the calculators on this page.
Start calculating
Not sure which calculator to use? Start with the repayment calculator if you are buying, or the balance calculator if you already have a mortgage and want to plan ahead.