How to use it
- Enter the amount you borrow, the annual interest rate (for example 6.5) and the term in years or months.
- Read the monthly payment, the total interest and the total amount you will pay.
- Optionally add an extra monthly payment to see how much sooner the loan ends and how much interest you save.
- Open the schedule by year to see every payment, or download it as a CSV file for a spreadsheet.
How it works
This is a standard fixed-rate amortizing loan (an annuity): every monthly payment is the same, and each one covers that month's interest first, with the rest reducing the balance. The monthly payment is M = P × r ÷ (1 − (1 + r)^−n), where P is the amount borrowed, r the monthly rate (the annual rate ÷ 12 ÷ 100) and n the number of monthly payments. With a 0% rate the payment is simply P ÷ n.
Each month, interest = remaining balance × r. Early on most of the payment is interest; towards the end most of it is principal. The schedule is calculated in whole cents: the payment and each month's interest are rounded to 2 decimals, and the final payment is adjusted by a few cents so the balance reaches exactly zero.
An extra monthly payment goes entirely to the principal. Because later interest is charged on a smaller balance, the loan ends sooner and the total interest falls; the regular payment stays the same.
These are estimates. Real loans may compound daily, charge arrangement fees or insurance, use a different day count, or have variable rates. The annual rate here is a nominal rate divided by 12, which is how most mortgages and car loans state it; it is not the APR, which also includes fees.
Examples
Mortgage
200,000 at 6% for 30 years: r = 0.06 ÷ 12 = 0.005 and n = 360, so M = 200,000 × 0.005 ÷ (1 − 1.005^−360) = 1,199.10 per month. Over 30 years you pay about 231,677 in interest.
Paying a little extra
On the same mortgage, an extra 200 a month pays the loan off in 252 payments instead of 360, 9 years earlier, and saves about 79,800 in interest.
Interest-free purchase
1,000 over 3 months at 0% is 333.33, 333.33 and a final 333.34, because the cents cannot be split evenly.
Frequently asked questions
Is the interest rate the APR?
No. Enter the nominal annual interest rate. The APR also includes fees and other charges, so it is usually higher. The calculator divides the annual rate by 12 to get the monthly rate.
Why does the first payment contain so much interest?
Interest is charged on the remaining balance, which is highest at the start. As the balance falls, the interest part shrinks and the principal part grows, while the total payment stays the same.
Why is my lender's payment slightly different?
Lenders may compound daily, count actual days per month, round differently or add fees and insurance to the payment. Differences of a few cents to a few units are normal.
Can I open the schedule in Excel or Google Sheets?
Yes. “Download CSV” saves a file with one row per month (payment, principal, interest, extra and balance) using a dot as the decimal separator.
Privacy
All figures are calculated in your browser. Loan details are not sent or stored, and the CSV file is created on your device.