Mortgage Calculator
What's My Mortgage Payment?
Calculate your monthly mortgage payment based on property price, deposit, interest rate and term.
Mortgage Details
Adding a regular overpayment can significantly reduce your interest costs and mortgage term.
Payment Summary
Enter your mortgage details and click calculate to see your payment breakdown.
Understanding Mortgage Payments
What your monthly payment really means
How your mortgage payment is calculated
Every repayment mortgage has a fixed monthly payment, but the split between principal and interest shifts dramatically over time. Early on, most of your payment covers interest on the large outstanding balance. As the balance falls, more of each payment chips away at the principal itself. This is called amortisation.
Principal
The portion of your payment that reduces your outstanding loan balance and builds your equity in the property.
Interest
The lender's charge for borrowing, calculated on your remaining balance each month. Dominates early payments, shrinks over time.
Fixed monthly total
On a repayment mortgage the amount stays the same throughout the term; only the internal principal/interest split changes.
Repayment vs interest-only
- Repayment: each payment reduces your balance. At the end of the term you own the property outright.
- Interest-only: lower monthly payments, but the full loan remains at the end. You need a separate repayment vehicle (savings, pension, or property sale) to clear it.
- Most residential buyers use repayment. Interest-only is more common in buy-to-let.
Fixed vs tracker/variable rates
- Fixed rate: payment stays the same for the deal period (typically 2–5 years), giving certainty in your budget.
- Tracker/variable: rate moves with the Bank of England base rate or the lender's SVR. Can be cheaper but unpredictable.
- When a fixed deal ends, you roll onto the lender's Standard Variable Rate (SVR), which is usually much higher. Remortgaging before expiry avoids this.
Overpayments
Paying more than your required amount each month directly reduces the principal, cutting both the term and the total interest you pay.
- Most lenders allow up to 10% of the outstanding balance per year without an early repayment charge
- Even £100/month extra on a £200k mortgage can save years off the term
- Check for early repayment charges before overpaying beyond the annual limit
The true cost of your mortgage
The headline loan amount is only the beginning. Over a full 25-year term, the total interest paid on a typical mortgage can exceed the original loan itself. A £250,000 mortgage at 4.5% over 25 years carries a monthly payment of around £1,389, with total interest of approximately £167,000 by the end.
- Reducing your rate by 0.5% on £250k saves roughly £20,000 in interest over 25 years
- Shortening your term from 25 to 20 years increases monthly payments but cuts total interest significantly
- Use the chart above to see how the principal/interest split evolves year by year
LTV improves over time
As you repay, your loan-to-value ratio falls. Every 5% reduction in LTV typically opens a cheaper rate band. By the time you remortgage after your first fixed deal, your LTV may have improved enough to qualify for a meaningfully lower rate. Worth checking every time.
Property taxes by region
The tax you pay on purchase depends on where you buy. England & N. Ireland use SDLT. Scotland uses LBTT. Wales uses LTT. All use a progressive band system, and first-time buyer reliefs apply in each nation. Budget for this alongside your deposit.
Arrangement & purchase fees
- Arrangement fee: lender's product fee, typically £500–£2,000. Can often be added to the mortgage, but you'll pay interest on it.
- Valuation fee: lender commissions a survey to confirm the property's value, usually £150–£500.
- Solicitor/conveyancing fees: legal costs for the transfer of ownership, typically £1,000–£2,500.
When to remortgage
- Start looking 6 months before your fixed deal expires — most offers can be locked in early
- Falling onto the SVR after a fixed deal typically adds hundreds per month
- Even a 0.5% rate improvement can save thousands over a new 2–5 year fix
Stress-testing your payment
Before committing to a mortgage, check whether you could still afford the payments if rates rose by 2–3%. Lenders run affordability stress tests at rates above their product rate for exactly this reason.
- Try adjusting the rate in the calculator above to see how your monthly payment changes
- A tracker mortgage leaves you fully exposed to base rate moves, so factor in a comfortable buffer
How much can you borrow?
Monthly payment is only part of the picture. Use the mortgage affordability calculator to work out your maximum borrowing based on income, deposit, and existing debts.
Educational guidance only. Not financial or mortgage advice. All figures are illustrative estimates based on typical rates and loan sizes. Actual monthly payments depend on your specific loan amount, term, interest rate, and lender conditions. Speak to a qualified mortgage adviser before making any decision.
Monthly payment is only part of the mortgage picture
Read the mortgage affordability guide for the wider context around deposits, lender checks, borrowing limits and mortgage trade-offs.