How to use the loan calculator
Enter the amount you plan to borrow, the annual interest rate and the length of the loan, then press Calculate. The term can be given in years, in months or as a mix of both, so a loan of 5 years and 6 months is simply 66 monthly payments.
The results show your fixed monthly payment, the number of payments, the total you will pay back and how much of that is interest. Below them is an amortization schedule. By default it lists one row per year; switch on Show monthly rows to see every single payment.
The loan payment formula
Most personal loans, auto loans and mortgages are amortizing loans: every payment is the same size, and each one covers that month's interest first, with the rest reducing the balance. The payment is found with the annuity formula:
M = P × r / (1 − (1 + r)^−n)
- M is the monthly payment
- P is the loan amount (principal)
- r is the monthly interest rate, which is the annual rate divided by 12 and by 100
- n is the number of monthly payments
If the interest rate is 0%, the formula reduces to M = P / n.
Worked example
Borrowing 200,000 at 6% a year for 30 years gives r = 0.005 and n = 360. The monthly payment is 200,000 × 0.005 / (1 − 1.005^−360) = 1,199.10. Over 360 payments you repay about 431,676.38, so the total interest is about 231,676.38.
In the first month the interest is 200,000 × 0.005 = 1,000.00, so only 199.10 goes toward the balance. As the balance falls, the interest part shrinks and the principal part grows.
Good to know
- The calculator assumes a fixed rate, equal monthly payments and no fees. Real loans may add origination fees, insurance or other charges, so treat the results as estimates.
- Amounts are calculated at full precision and rounded to cents for display, so a lender's schedule may differ by a few cents.
- A shorter term raises the monthly payment but usually cuts the total interest a lot.
- Paying extra toward principal early in the loan reduces the interest you pay over its life.