UK Loan Repayment Calculator

This calculator uses a standard amortising loan formula. APR is converted into a monthly rate, the term is converted into months, and the payment is calculated so the balance reaches zero by the end of the term if every payment is made on time.

The annual summary walks through the same calculation month by month. Each payment first covers the interest charged on the outstanding balance, then the remainder reduces the principal. Early in the loan, more of the payment is interest; later, more goes to principal. APR is not the same as a flat rate, so two loans with the same monthly payment can still have different total costs.

Use the result as a practical planning estimate for loan amount, apr, term in months or years, monthly repayment, total interest, year-by-year amortisation. The calculator is designed to make the main moving parts visible immediately, so it is most useful when you want to compare scenarios, sense-check a decision, or understand why one input changes the final result.

Before relying on the number, check whether your situation includes anything outside the calculator scope. Common examples are local rules, provider fees, payroll timing, special reliefs, bank holidays, tariff changes, exchange-rate markups, unusual tax codes, or personal circumstances that need official guidance or professional advice.

To make the estimate more accurate, use figures from the most recent bill, payslip, lender quote, receipt, official notice or provider screen you have. Rounded inputs are fine for quick comparisons, but precise inputs are better when you are deciding whether something is affordable or comparing two similar options.

Re-run the calculator whenever a key assumption changes, such as a new rate, different term, changed salary, updated threshold, extra fee, altered usage pattern or different date range. Keeping those assumptions fresh is often more useful than trying to make one calculation perfect.

If you are using the result for a formal decision, keep a note of the inputs you used and the date of the calculation. That makes it easier to compare the estimate with a later quote, bill, payslip or official calculation.