Mortgage Calculator
Monthly payments, total interest, and full amortisation schedule — for repayment and interest-only mortgages. Overpayment calculator included.
Where are you based?
Sets your currency and typical interest rate.
How the Mortgage Calculator Works
Enter your loan details and get a full breakdown in seconds — no signup, no data stored.
Enter your loan amount
Type in the total amount you need to borrow — not the property price. For a £300k property with a £60k deposit, enter £240k.
Set your rate and term
Enter your agreed interest rate as a percentage and select your mortgage term. Rates are pre-filled by country but you can override them.
Choose repayment type
Repayment mortgages pay off capital and interest together. Interest-only mortgages pay just the interest — the full capital is due at the end.
Add overpayments (optional)
If you plan to overpay each month, enter the amount. The calculator shows how many years you save and the total interest reduction.
Frequently Asked Questions
How is the monthly mortgage payment calculated?
For a repayment mortgage, the formula is: M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of months. For an interest-only mortgage, you simply pay the interest each month: M = P × r, and repay the full capital at the end of the term.
What is the difference between a repayment and an interest-only mortgage?
With a repayment mortgage, each monthly payment covers both interest and a portion of the capital, so the loan is fully paid off at the end of the term. With an interest-only mortgage, you only pay the interest each month — the full capital amount remains outstanding and must be repaid in a lump sum at the end of the term.
What is an amortisation schedule?
An amortisation schedule is a complete table showing every monthly payment over the life of the mortgage. It breaks each payment into its interest and capital components and shows the remaining balance after each payment. In the early years, most of your payment goes towards interest. Over time, the proportion going to capital increases.
Does making overpayments save money?
Yes — significantly. An overpayment reduces the outstanding capital, which means less interest accrues each month. Even a small monthly overpayment can shorten the mortgage term by several years and save thousands in interest. Our calculator shows you the exact impact: enter an overpayment amount to see the revised schedule and total savings.
What is LTV (loan-to-value)?
LTV is the ratio of your mortgage to the value of the property, expressed as a percentage. A £180,000 mortgage on a £200,000 property is a 90% LTV. Lenders use LTV to set interest rates — the lower your LTV, the better the rate you can typically access. Most competitive rates start at 60% LTV.
What is the best free mortgage calculator?
ToolStack's mortgage calculator is completely free with no signup required. It supports repayment and interest-only mortgages, overpayments, a full amortisation schedule, and 15 currencies — all in one tool. Unlike bank calculators, it doesn't push you to apply or collect your data.
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