Mortgage and home purchase planner
An illustrative mortgage planner covering repayment and interest-only mortgages, overpayments, rate changes, remortgaging and purchase costs. Your financial inputs stay in this session only — they are not stored or sent. This is not mortgage advice.
Mortgage type
Choose a repayment mortgage (capital and interest) or an interest-only mortgage.
Loan amount
Enter the property price and deposit, or switch to an existing balance.
Interest rate and term
The annual interest rate and the mortgage term in years.
Overpayments
Optional extra payments. Choose to reduce the term or reduce monthly payments. Lender behaviour varies — do not assume a universal penalty-free allowance.
Rate change
Model an initial rate for a fixed period, then an assumed subsequent rate. The monthly payment is recalculated when the rate changes.
Remortgage comparison
Compare your current mortgage with a replacement rate and term. Includes product fees and compares over a common period — not just the monthly payment.
Home purchase funds
Deposit plus purchase costs, less available savings. Property transaction tax (SDLT/LTT) is a user-supplied amount — this tool does not calculate it.
Cannot calculate yet
Enter a property price and deposit (or an existing balance) to calculate a loan amount.
How interest is calculated: Interest is calculated as annual rate ÷ 12, applied monthly to the remaining balance. This is a simplified approximation — actual lenders typically calculate interest daily, so real figures may differ slightly.
Overpayments: Reduce-term keeps the payment the same and shortens the mortgage; reduce-payment keeps the term the same and lowers the payment. Lender behaviour varies — some recalculate at different intervals. Overpayment limits, their basis, reset dates and charges vary by lender and product. This tool does not assume a universal penalty-free allowance.
Rate changes and remortgaging: The subsequent rate is an assumption, not a forecast. The remortgage comparison shows monthly payment, total cost and remaining balance over a common period — do not compare deals solely by monthly payment. Product fees can be paid upfront or added to the loan.
Home purchase funds: Property transaction tax (SDLT/LTT/LBTT) is a user-supplied amount — this tool does not calculate it. Use the official government calculator or ask your conveyancer.
Interest-only: Interest-only payments do not repay the capital. You will still owe the full loan at the end of the term unless you have a separate repayment plan.
Privacy: all financial inputs are held in temporary browser memory for this session only and are never stored, sent, or transmitted. The hosting platform may log page views and collect performance telemetry; those logs contain no financial figures.