Mortgage Calculator

The largest interest bill of most people's lives

A mortgage is usually the biggest loan a person ever takes and, because of its length, the interest is startling when you actually total it. Borrow a substantial sum over thirty years at a typical rate and the interest alone can approach or exceed the amount borrowed — meaning you repay something close to twice the price of the house. That figure rarely appears in any conversation during a purchase, because every party to the transaction is focused on whether the monthly payment fits your income. Calculating the total repayment before you commit is not pessimism; it is the only way to see the actual price of the decision, and it is what makes the case for a larger deposit, a shorter term or a better rate concrete rather than abstract.

Small rate differences, enormous consequences

Because a mortgage compounds over decades on a large balance, the interest rate exerts far more leverage than its size suggests. The gap between 4.5% and 5.5% sounds like almost nothing and, on a long large loan, can amount to a difference of tens of thousands in total interest. This is why the boring, unglamorous work pays so well here: improving your credit score before applying, saving a larger deposit to reach a better loan-to-value band, and genuinely shopping between lenders rather than accepting the first offer. A week of effort in the run-up to an application routinely outperforms years of budgeting elsewhere in the household.