Amortization calculator

Calculate a level loan payment, month-by-month principal and interest, and the effect of an extra monthly payment.

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Loan principal

Annual interest percent

More inputs and assumptions

Term in months

Extra monthly payment

Answer

…

Calculate a level loan payment, month-by-month principal and interest, and the effect of an extra monthly payment.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Saved scenario

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Formula and assumptions

Automatic precision shows money to two decimal places and other numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Amortization calculator

Calculate a level loan payment, month-by-month principal and interest, and the effect of an extra monthly payment.

Next: Basic calculator

A worked example

With loan principal = 1200, annual interest percent = 0, term in months = 12, extra monthly payment = 0, the scheduled monthly payment is 100.00 (rounded to two decimal places).

Before you use the result

Assumes monthly interest at annual rate ÷ 12, a fixed rate, and payments at month-end. No daily accrual, fees, taxes, insurance, changing rates, or prepayment penalties. The model keeps unrounded balances; schedule rows show cents and may differ slightly from a lender’s rounding. Maximum 1,200 months. Calculations keep full browser-number precision. Money amounts are displayed to two decimal places; other results use up to 12 significant digits. Very large values may lose precision.

Example results for loan principal

These examples use Annual interest percent: 0; Term in months: 12; Extra monthly payment: 0. They are reference calculations, not recommended settings.

Loan principal	Scheduled monthly payment
600	50.00
1200	100.00
2400	200.00

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