UK Mortgage Calculator
Estimate your monthly mortgage repayment, total interest and total amount payable. Enter your property price, deposit, interest rate and mortgage term, or use the remortgage and rate comparison tools to explore different scenarios.
Mortgage payment calculator
Deposit and LTV
Other purchase costs (optional)
These optional costs are shown separately and are not added to the mortgage balance. Stamp Duty is not included; use the dedicated Stamp Duty Calculator for that estimate.
Remortgage calculator
Compare your current repayment schedule with a new deal. Monthly payment differences are shown separately from the longer-term comparison. The longer-term comparison uses your current remaining mortgage term as a common horizon, then includes any balance still outstanding on the new mortgage at that point.
Mortgage rate comparison
Copyable results
How this mortgage calculator works
The repayment calculation uses the standard amortisation formula. The monthly interest rate is the annual rate divided by 12, and the number of payments is the mortgage term in years multiplied by 12.
Monthly payment: M = P × r × (1+r)n ÷ ((1+r)n − 1), where P is the loan, r is the monthly rate and n is the number of monthly payments. At 0% interest, the calculator uses the simple result P ÷ n.
Total interest: monthly payment × number of payments − original loan. Displayed figures are rounded to the nearest penny, but intermediate calculations retain full precision.
Remortgage comparison: monthly payments are compared directly. The longer-term comparison uses the current remaining mortgage term as the common horizon, then includes the new mortgage’s remaining balance and switching costs at that point. This avoids treating two different mortgage terms as though their total-payment figures were directly equivalent.
This is an illustrative repayment-mortgage calculator. It does not model daily lender interest, product fees added to the loan, overpayments, payment holidays, rate changes, tax, insurance, or other lender-specific terms.
What does this mortgage calculator calculate?
This UK mortgage calculator estimates the monthly repayment on a standard capital-and-interest mortgage. It also shows the total amount payable over the selected term, the total interest, your loan-to-value (LTV) and the cash needed upfront from the figures you enter.
The calculator does not use a live mortgage rate. Enter the interest rate from the mortgage deal or example you want to test. This keeps the calculation useful even when mortgage rates change.
Mortgage repayment vs mortgage affordability
A repayment calculator tells you what a particular mortgage could cost each month. It does not tell you whether a lender will approve that borrowing. Lenders assess affordability using factors such as income, outgoings, existing commitments and their own lending criteria.
If you want to estimate how much you might be able to borrow, use our Mortgage Affordability Calculator instead.
How mortgage repayments are calculated
The calculator uses the standard amortisation formula for a repayment mortgage. The annual interest rate is converted to a monthly rate and the loan is spread across the number of monthly payments in the selected term. At 0% interest, the calculation simply divides the loan by the number of payments.
How does the mortgage term affect the cost?
A longer mortgage term usually lowers the required monthly payment because the balance is repaid over more months. However, if the interest rate stayed unchanged, the longer term would normally result in more interest being paid overall.
| Example: £200,000 at 5% | Monthly payment | Total interest |
|---|---|---|
| 15 years | £1,581.59 | £84,685.71 |
| 20 years | £1,319.91 | £116,778.75 |
| 25 years | £1,169.18 | £150,754.02 |
| 30 years | £1,073.64 | £186,511.57 |
What is LTV?
Loan-to-value (LTV) compares the mortgage balance with the property’s value. For example, a £200,000 mortgage on a £250,000 property has an 80% LTV. LTV is one factor lenders may use when pricing mortgage products, but the calculator does not predict the rate you will be offered.
What is included in the upfront figure?
The calculator adds your deposit to the optional survey, legal and broker costs you enter. It does not include Stamp Duty, moving costs, insurance, lender-specific product fees or other costs unless you enter them in the available fields.
Methodology reviewed: August 2026. Mortgage rates, lender criteria and other market conditions can change, so enter the rate and terms relevant to the mortgage you are considering.
Important assumptions
- The mortgage is a standard capital-and-interest repayment mortgage.
- The entered annual interest rate is assumed to remain constant for the calculated term.
- Interest is modelled monthly using the standard amortisation method.
- Displayed figures are rounded to the nearest penny, while intermediate calculations retain full precision.
- Fees entered as purchase or switching costs are treated as paid separately and are not added to the mortgage balance.
- The calculator does not predict which mortgage rate or borrowing amount a lender will offer you.
Frequently asked questions
How accurate is this mortgage calculator?
The underlying calculation uses the standard repayment-mortgage amortisation formula, so it provides a consistent mathematical estimate for the loan, rate and term entered. A lender’s actual illustration can differ because lenders may use different interest-calculation conventions, fees, rounding and product terms.
What is the difference between mortgage term and product term?
The mortgage term is the total period used to repay the loan. The product term is the period for which a fixed, discounted or other deal applies. This calculator keeps those concepts separate in the remortgage section.
Does a lower monthly payment always mean a better mortgage?
No. A longer term can reduce the monthly payment while increasing the total interest paid. Compare both the monthly payment and the longer-term cost rather than relying on the monthly figure alone.
What is an early repayment charge?
An early repayment charge (ERC) is a fee a lender may apply when you repay or switch a mortgage before the relevant product terms allow you to do so without that charge. The calculator lets you enter the amount rather than assuming a particular lender’s ERC rules.
How does the remortgage comparison work?
The remortgage comparison uses the current remaining mortgage term as a common comparison period. It compares the payment streams, includes switching costs, and includes any balance still outstanding on the new mortgage at the end of that period. It assumes the entered rates remain unchanged for the comparison and is therefore an illustration rather than a forecast.
How does LTV affect a mortgage?
Loan-to-value is the mortgage balance expressed as a percentage of the property’s value. Lenders commonly use LTV bands when pricing products, so a lower LTV can give access to different products and rates. This calculator shows the mathematical LTV only and does not predict lender pricing.
Does the calculator include mortgage fees?
Purchase and remortgage costs can be entered separately. They are shown as upfront or switching costs and are not added to the loan balance, so the calculator does not charge interest on those fees.
Can I use this for an interest-only mortgage?
No. The payment formula assumes capital and interest are repaid over the term. Interest-only mortgages require a different model because the principal normally remains outstanding until repayment or refinancing.