Amortisation Schedule Calculator

An amortisation schedule is the payment-by-payment breakdown of a loan, showing how each payment splits between interest and principal and how the remaining balance shrinks over time. The defining characteristic of standard amortisation is that the early years are mostly interest, and the later years are mostly principal, even though the monthly payment stays constant. This calculator surfaces the year-1 figures (the interest-heavy end of the schedule) plus the lifetime totals.

How to use it

Enter the loan amount (the principal borrowed), the annual interest rate, and the term in years. The calculator returns the monthly payment, the interest paid in year 1, the principal paid in year 1, the balance at the end of year 1, the total interest paid over the full term, the total amount paid over the full term, and the first month in which the principal portion of the payment exceeds the interest portion.

What the inputs mean

Loan amount is the principal, meaning the amount actually borrowed rather than the property price. Annual rate is the headline rate quoted by the lender, entered as a percentage (5 for 5%, not 0.05). Term is the loan length in years. The calculator assumes a fixed rate, fixed monthly payment, and no overpayments or missed payments, which matches the contractual structure of most fixed-rate mortgages, personal loans, and car loans.

The front-loaded interest pattern

Each month's interest equals the remaining balance multiplied by the monthly rate. At the start of the loan the balance is at its maximum, so the interest portion of the payment is also at its maximum. As the balance falls, the interest portion shrinks, and because the total payment is constant, the principal portion grows. The month where principal first exceeds interest is reported in the panel. Its position depends on the rate and the term and never on the size of the loan: at a fixed term it falls later as the rate rises, so a 25-year loan crosses over near month 93 at 4%, month 135 at 5% and month 163 at 6%.

A worked example

Numbers below are illustrative units. The calculator displays them in your selected currency. With a loan amount of 200,000, an annual rate of 5%, and a 25-year term, the monthly payment is about 1,169.18, of which year 1 splits into about 9,906.35 of interest and about 4,123.81 of principal. The panel carries the balance and the lifetime totals alongside.

Why early overpayments save more interest

An overpayment removes principal from the balance that every later month's interest is charged on, so what the saving tracks is the number of months still to run, not the interest share of the payment at the time. The same amount paid in the first year avoids interest across almost the whole term; paid in the final year it avoids interest across the months that remain, which is very little. The gap between the two is large and widens with both the rate and the remaining term.

Standard amortisation vs interest-only

This calculator models standard amortisation, where the principal reduces each month. Interest-only loans pay only the interest each month with the full principal due at the end of the term. Investment-property loans are interest-only in some markets, while loans on an owner-occupied home are more commonly amortising. An interest-only loan has a lower monthly payment for the same principal and rate, but the borrower still owes the full original principal at the end of the term, and needs a separate plan to repay it.

What this tool does not capture

The calculator assumes a fixed rate, fixed payment, no overpayments, no missed payments, no rate resets, and no fees. It also does not separately model rate-fix periods (common on mortgages, where the headline rate applies for an initial period and then changes). For rate-fix modelling, run the calculation at the initial rate to see year-1 figures, and re-run at the post-fix rate to see what changes. The tool does not model offset or redraw facilities, escrow or impound arrangements, sinking funds, or the tax treatment of loan interest in any particular jurisdiction.