Loan Payment Calculator

What this calculator does

This calculator works out the fixed payment for a standard amortised loan — the kind used for most personal loans, car loans and home loans. Each payment covers the interest that accrued since the last payment, and the remainder reduces the balance. Because the balance falls over time, the interest portion shrinks and the principal portion grows, even though the payment itself stays the same.

Alongside the payment, it shows the total interest over the life of the loan, the total amount you would repay, and a year-by-year schedule of how the balance falls. If you add an optional extra payment, it also shows how much interest and time that could save.

What each input means

Amount you want to borrow — the principal, before any fees.

Annual interest rate — the nominal yearly rate quoted by the lender. The calculator divides it by the number of payments per year to get the per-period rate.

Repayment period — how long you will take to repay, in months or years.

Payment frequency — how often you pay. Monthly is the most common; fortnightly and weekly payments repay slightly faster for the same annual amount because interest is charged on a lower balance sooner.

Upfront fees — one-time charges such as processing or origination fees. They are added to the total cost but are assumed to be paid separately, not borrowed.

Extra payment — an optional amount added to every payment. It goes entirely toward the principal, which shortens the loan and reduces total interest.

What changes the result most

The interest rate and the repayment period dominate the total cost. A longer period lowers each payment but increases the total interest, because the balance stays higher for longer. Comparing the same loan over two different periods — or two lenders' rates over the same period — usually reveals a bigger difference than any fee.

Formula

For a per-period interest rate i (annual rate ÷ payments per year, as a decimal), a principal P and n total payments, the fixed payment is: payment = P × i ÷ (1 − (1 + i)⁻ⁿ).

When the interest rate is 0%, the payment is simply P ÷ n.

Each period, interest = outstanding balance × i. The principal portion is the payment minus that interest, plus any extra payment. The final payment is reduced so the balance lands exactly on zero.

Assumptions

• Interest accrues per payment period at the nominal annual rate divided by the number of payments per year.
• Payments are made at the end of each period, starting one period after the start date.
• The interest rate stays fixed for the whole term.
• Extra payments are applied directly to the principal in the same period, with no prepayment penalty.
• Upfront fees are paid separately — they are not added to the borrowed amount and accrue no interest.
• Amounts are calculated at full precision and rounded for display, so columns may differ from totals by a small rounding amount.

Content and formulas reviewed on 2026-08-06. See our methodology for how calculations are built and tested.

Worked example

Suppose you borrow 1,000,000 at 8.5% per year for 20 years with monthly payments. The per-period rate is 8.5% ÷ 12 ≈ 0.7083% and there are 240 payments.

Payment = 1,000,000 × 0.007083 ÷ (1 − 1.007083⁻²⁴⁰) ≈ 8,678 per month.

Over 240 payments you would repay about 2,082,776 in total, of which about 1,082,776 is interest — more than the amount borrowed. Adding an extra 2,000 per month would clear the same loan roughly 6 years sooner and save roughly 350,000 of that interest, based on these inputs.

Frequently asked questions