UK Mortgage Calculator
Estimate monthly mortgage payments, Stamp Duty Land Tax, and your full amortization schedule.
How the UK Mortgage Calculator Works
Our UK mortgage calculator helps you estimate your monthly home loan payments by taking into account the property price, deposit, interest rate, mortgage term, council tax, and service charge. It also calculates Stamp Duty Land Tax (SDLT) for your purchase, including first-time buyer relief and the additional property surcharge.
Mortgage Payment Formula
The monthly principal and interest payment uses the standard amortization formula:
M = P × [ r(1+r)n ] / [ (1+r)n − 1 ]
Where M is the monthly payment, P is the mortgage amount (property price minus deposit), r is the monthly interest rate, and n is the total number of monthly payments.
For example, a £240,000 mortgage (after a £60,000 deposit on a £300,000 property) at 5.5% over 25 years gives a monthly payment of about £1,471. Add £150 monthly council tax for a total of £1,621.
Stamp Duty Land Tax (SDLT) — England & Northern Ireland
SDLT is charged in bands on the property price. For standard purchases (2024/25):
- 0% up to £250,000
- 5% on £250,001 – £925,000
- 10% on £925,001 – £1,500,000
- 12% above £1,500,000
First-time buyers pay 0% up to £425,000 and 5% on £425,001–£625,000 (relief ends above £625,000). Additional property buyers pay a 5% surcharge on top of the standard rates. Scotland uses Land and Buildings Transaction Tax (LBTT) and Wales uses Land Transaction Tax (LTT), which have different bands.
What Is Included in Your Monthly Payment?
- Principal: The portion that reduces your mortgage balance.
- Interest: The cost of borrowing, based on your rate and remaining balance.
- Council Tax: A local tax based on your property's valuation band (A–H in England). Annual amount divided by 12.
- Service Charge: For leasehold properties (flats and some houses), covers building maintenance, insurance, and communal areas.
Fixed-Rate vs. Variable-Rate Mortgages
Most UK mortgages start with a fixed-rate period of 2, 3, 5, or 10 years. During this period, your interest rate and monthly payment stay the same. After the fixed period ends, you typically revert to the lender's Standard Variable Rate (SVR), which is usually higher. Most borrowers remortgage to a new fixed deal at this point. This calculator models a fixed-rate mortgage for the full term — to model an initial fixed period, use the fixed rate for the first few years and understand that you'll likely remortgage.
Deposit Requirements
The minimum deposit for a UK mortgage is typically 5% of the property price, though 10% is more common and gives access to better rates. A 15–25% deposit unlocks the best interest rates. Unlike the US, the UK does not have private mortgage insurance — instead, a smaller deposit simply means a higher interest rate. Some lenders charge a Higher Lending Charge for deposits below 10%, but this is increasingly rare.
Tips for Lowering Your Mortgage Payment
- Save a larger deposit to access lower interest rates.
- Compare deals from multiple lenders — use a mortgage broker if needed.
- Consider a longer term for lower monthly payments (but more total interest).
- Improve your credit score before applying.
- Look at product fees (arrangement fees) — some low-rate deals have high fees that offset the savings.
- Overpay when you can — most lenders allow 10% overpayments per year without penalty.
Frequently Asked Questions
Stamp Duty Land Tax (SDLT) is a tax you pay when buying a property in England and Northern Ireland. The amount depends on the property price, whether you're a first-time buyer, and whether it's an additional property. Scotland has its own Land and Buildings Transaction Tax (LBTT), and Wales has Land Transaction Tax (LTT).
First-time buyers in England and Northern Ireland pay no SDLT on properties up to £425,000, and 5% on the portion from £425,001 to £625,000. The relief applies to properties valued at £625,000 or less. Above £625,000, standard SDLT rates apply.
Most UK mortgages have a total term of 25 years, though terms of 30–35 years are increasingly common. The interest rate is typically fixed for an initial period of 2, 3, 5, or 10 years, after which it reverts to the lender's Standard Variable Rate (SVR) unless you remortgage.
A fixed-rate mortgage keeps the same interest rate for an agreed period (typically 2–5 years), giving you payment certainty. A variable rate mortgage (tracker or SVR) can go up or down with the Bank of England base rate. This calculator models a fixed-rate mortgage.