Loan calculator

For a loan with constant payments, the monthly payment is P × r / (1 − (1 + r)^−n), where P is the principal, r the monthly rate (annual rate / 12) and n the number of payments. Each month, interest is calculated on the outstanding balance: it weighs heavily at the start of the loan, then the share of principal repaid grows.

The calculator uses the nominal rate, the one used to calculate interest in your contract. The APR adds mandatory insurance, arrangement and guarantee fees: it is used to compare offers. Enter the insurance and fees to get the real total cost of the loan.

Calculated on the amount borrowed, insurance is the same every month. Calculated on the outstanding balance, it decreases as you repay and often costs less overall. Compare both with your offer before signing.

Constant payments: the same monthly payment from start to finish, the most common case. Constant principal: the same share of principal each month, higher payments at first that then decrease, and less interest overall. Interest-only: you only pay the interest, the principal is repaid in one go at the end (bridging loan, buy-to-let).

The longer the term, the lower the monthly payment, but the higher the total cost: interest runs for longer. For a mortgage, terms often range from 15 to 25 years, and your debt ratio (payments / income) should generally not exceed 35%, insurance included. Compare two terms in the calculator: the difference in total cost is often significant.

It details each loan payment: its date, its amount, its share of interest, principal and insurance, then the outstanding balance. It shows that interest weighs heavily at the start of the loan, and gives the outstanding balance at a given date (useful for an early repayment or a resale). The calculator presents it by year and saves it as a PDF.