How to use the loan calculator
- Enter the loan amount and the interest rate (APR).
- Enter the term as years plus extra months. For example, 2 years and 6 months, or 0 years and 30 months.
- Optional: open More options to add an extra monthly payment and a start date to see the payoff date.
- Read the monthly payment, total interest and number of payments. The yearly table summarizes the loan and the CSV has every month.
Formula
Monthly rate r = APR / 12; number of payments n = years x 12 + months
Payment = Amount x r / (1 - (1 + r)^-n), rounded to the cent
Each month: interest = remaining balance x r (rounded to the cent); the rest of the payment reduces the balance
Final payment = remaining balance + that month's interest
With a 0% rate the payment is the amount divided by the number of payments. An extra payment is added to each regular payment and goes straight to principal.
Worked example: a $20,000 loan at 5%
Over 60 months the payment is $377.42. In month 1, interest is $20,000 x 0.05 / 12 = $83.33. Total interest over the loan is $2,645.52, so you repay $22,645.52. The last payment is $377.74 because it absorbs the cents lost to rounding.
Adding $100 a month ends the loan after 47 payments instead of 60, which is 13 months sooner. Total interest drops to $2,025.41, saving $620.11.
With a start date of January 15, 2026 and the first payment one month later, the 60-payment loan ends on January 15, 2031. With the $100 extra it ends December 15, 2029.
What this calculator is for
Use it for any fixed-rate installment loan where you repay equal monthly amounts: personal loans, student loans, home improvement loans or a loan from a family member. For a house, the mortgage calculator adds tax and insurance. For a vehicle, the car payment calculator handles trade-in and sales tax.
APR versus the rate on the note
A loan's APR can include some fees, while the note rate does not. If your lender quotes both, the note rate gives the most accurate payment, and the APR is better for comparing offers. If a loan has an origination fee that is subtracted from the amount you receive, enter the amount you actually borrow before the fee and compare the totals yourself.
Extra payments and prepayment
Extra payments shorten the loan and cut interest, but check whether your loan has a prepayment penalty and whether extra money is applied to principal rather than held for the next due date. Many lenders let you specify this online or on the payment slip.
Assumptions and limits
- A fixed rate, equal monthly payments and monthly compounding. Variable-rate and interest-only loans are not modeled.
- The first payment is due one month after the start date, and every later payment is one calendar month after the previous one.
- Interest is calculated on the running balance each month and rounded to the cent. Some lenders accrue interest daily, which can change totals slightly.
- Origination fees, late fees, insurance and taxes are not included.
- The term can be up to 50 years. The extra payment, if any, is applied in full to principal every month.
- This is an estimate, not financial advice or a loan offer.
Frequently asked questions
How do I calculate a loan payment?
Use the amortization formula with the loan amount, the monthly rate (APR divided by 12) and the total number of monthly payments. This page does the math and also lays out the month-by-month schedule.
Can I enter the term in months only?
Yes. Put 0 in years and the number of months in the months field, such as 0 years and 30 months. You can also mix them, so 4 years and 12 months equals 5 years.
What happens at a 0% interest rate?
The loan is split evenly. A $12,000 loan over 2 years at 0% costs $500.00 a month with no interest, and the schedule shows zero interest each month.
Why is the last payment different?
The regular payment is rounded to the nearest cent, so tiny differences build up over many months. The last payment clears whatever balance remains, which is why it can be a few cents higher or lower.