UK Mortgage Calculator
Estimate a UK repayment or interest-only mortgage payment, loan-to-value, arrangement-fee financing and overpayment effect.
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Change any assumption and calculate again to compare results.
Repayment and interest-only mortgages
A repayment mortgage pays interest and principal each month so the balance is scheduled to reach zero by the end of the term. An interest-only mortgage normally pays only interest each month, leaving the capital balance to be repaid separately at the end. This calculator supports both structures and clearly labels the outstanding principal.
For repayment loans, the calculator uses the standard fixed-payment formula. For interest-only loans, the base monthly payment is the mortgage balance multiplied by the annual rate and divided by 12. Real UK mortgages can have changing rates, introductory periods and product fees, so treat this as a planning estimate.
Deposit, LTV and arrangement fees
Loan-to-value, or LTV, compares the mortgage balance with the property price. A larger deposit lowers LTV and reduces the amount borrowed. If you choose to finance the arrangement fee, it is added to the mortgage balance and therefore also earns interest.
If you pay the fee upfront, the fee does not increase the mortgage balance. This is useful when comparing products that advertise different rates but charge materially different fees.
Overpayments
For a repayment mortgage, an optional monthly overpayment is simulated against the balance. The result shows an estimated earlier payoff time and interest saving.
Lenders can impose annual overpayment limits or early-repayment charges during fixed-rate periods. Check your mortgage offer before assuming every overpayment can be made without cost.
Frequently Asked Questions
What is LTV on a UK mortgage?
Loan-to-value is the mortgage amount divided by the property value, expressed as a percentage.
Does this include stamp duty?
No. The calculator focuses on mortgage financing. Stamp duty and other purchase costs should be budgeted separately.
Can I model an interest-only mortgage?
Yes. Choose interest-only to estimate the monthly interest payment and the capital balance that remains outstanding.