Free mortgage calculator

How much will your mortgage cost?

Estimate your monthly repayments, stamp duty, and total cost of buying. Adjust the numbers to match your situation.

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How it works

Enter price

Type the property price or use a pre-filled link

Set deposit

Choose your deposit percentage with the slider

Pick a term

Select 15–35 years and adjust the interest rate

See results

Instant monthly payment, stamp duty, and total cost

How is my monthly mortgage payment calculated?

UK mortgage lenders use the annuity formula for repayment mortgages. The formula calculates a fixed monthly payment that covers both interest and capital repayment so that the loan is fully repaid at the end of the term. The key variables are: the loan amount (property price minus your deposit), the annual interest rate, and the mortgage term in years. Early in the mortgage, most of your payment goes towards interest. Over time, the balance shifts towards capital repayment.

How much deposit do I need for a mortgage in the UK?

The minimum deposit accepted by most UK lenders is 5% of the property price. However, a larger deposit reduces your loan-to-value (LTV) ratio, which typically unlocks lower interest rates. Here is a general guide to how deposit size affects your mortgage:

DepositLTVImpact on rate
5%95%Highest rates; limited lender choice
10%90%More lender options, slightly better rates
15–20%80–85%Competitive rates; most popular bracket
25%+75% or lessBest available rates

What affects mortgage interest rates in the UK?

Several factors determine the interest rate a lender will offer you: the Bank of England base rate (which influences all UK lending), your loan-to-value ratio (lower LTV = better rate), your credit score, the mortgage term, and whether you choose a fixed or variable rate product. Fixed rates give payment certainty for a set period (typically 2 or 5 years), while variable rates track the base rate or the lender's standard variable rate and can change monthly.

Stamp duty rates for 2025/26 (England & Northern Ireland)

Stamp Duty Land Tax (SDLT) is paid when you buy a property in England or Northern Ireland above a certain price. It is calculated in bands — you only pay each rate on the portion of the price within that band, not on the entire purchase price.

Standard rates

Up to £250k0%
Up to £925k5%
Up to £1,500k10%
Over £1,500k12%

First-time buyer relief

Properties up to £625,000

Up to £425k0%
Up to £625k5%

What is a Mortgage in Principle?

A Mortgage in Principle (MIP) — also called an Agreement in Principle (AIP) or Decision in Principle (DIP) — is a conditional statement from a lender confirming how much they would be willing to lend you. It involves a soft credit check and is typically valid for 60–90 days. Having an MIP shows sellers that you are a serious buyer with confirmed borrowing capacity, which can make your offer significantly more competitive.

Strengthen your offer with a Mortgage in Principle

Buyers with an MIP are taken more seriously by sellers. Get a free, no-obligation MIP through Boon Brokers (FCA No. 973757).

Get a Mortgage in Principle

Frequently asked questions

How accurate is this mortgage calculator?▾

This calculator uses the standard annuity formula used by UK mortgage lenders. Results are estimates based on the inputs you provide. Your actual mortgage offer may differ based on your credit score, the lender's criteria, and current market conditions. Always speak to a qualified mortgage adviser for personalised advice.

What deposit do I need for a mortgage in the UK?▾

Most UK lenders require a minimum deposit of 5% of the property price. However, a larger deposit (typically 10-20%) will usually secure a better interest rate, as you represent lower risk to the lender. First-time buyers may access government schemes that can help with deposits.

What is a Mortgage in Principle?▾

A Mortgage in Principle (MIP), also called an Agreement in Principle (AIP), is a conditional commitment from a lender confirming how much they would likely lend you. It is not a guarantee, but it shows sellers and estate agents that you are a serious buyer with borrowing capacity. Most MIPs are valid for 60-90 days.

How does stamp duty work in England?▾

Stamp Duty Land Tax (SDLT) is calculated in bands. You pay 0% on the first £250,000, 5% on the portion from £250,001 to £925,000, 10% from £925,001 to £1,500,000, and 12% on anything above. First-time buyers pay 0% up to £425,000 and 5% up to £625,000 on properties costing no more than £625,000.

Should I get a fixed or variable rate mortgage?▾

Fixed rates give you certainty — your monthly payment stays the same for the fixed period (typically 2 or 5 years). Variable rates may start lower but can change with the Bank of England base rate. The right choice depends on your financial circumstances and risk tolerance. Speak to a mortgage adviser for personalised guidance.

open for offer is not authorised to provide mortgage advice. All calculations are estimates for illustrative purposes only and should not be relied upon when making financial decisions. For personalised mortgage advice, speak to a qualified, FCA-regulated mortgage adviser. Stamp Duty Land Tax rates shown apply to England and Northern Ireland only. Scotland uses LBTT and Wales uses LTT, which have different rates and thresholds.