Solve for either the monthly payment or the loan term you need — whichever you're missing.
Switch between two modes: given a loan amount, rate and term, the calculator finds your required payment using the standard annuity PMT formula. Flip to 'Loan Term' mode and enter a payment you can afford — the calculator inverts the formula to find how many months you need. Extra payments are supported in payment mode and reduce the effective payoff period.
Monthly payment (PMT)
Monthly payment = Principal × monthly_rate / (1 − (1 + monthly_rate)^−n)
Solve for term (NPER)
n = −ln(1 − P × r / M) / ln(1 + r)
Any amount above your scheduled payment goes directly to principal. Reducing the balance faster means less interest accrues each month, shortening the total loan life. The calculator re-runs the full amortization schedule with the extra payment to show you the true payoff date.
A fixed monthly interest payment is due even if you pay nothing extra toward principal. If your target payment is at or below the interest portion of the first month, the loan can never be paid off. You'll see the required minimum amount in the error message.
Yes. When the interest rate is 0%, the payment is simply the principal divided by the number of months, and the term formula reduces to principal ÷ payment.
This calculator models a standard fixed-rate, fully-amortizing loan where every payment is the same. It works for personal loans, car loans, student loans and mortgages. It does not model interest-only periods, variable rates or balloon payments.