Loan Payment Calculator
Any fixed-rate loan: personal loan, student loan refinance, furniture financing. See your payment, total interest, and a full amortization table.
How this calculator works
This is the standard fixed-rate amortization formula every lender uses for installment loans: a flat payment every month that's split between interest and principal, with the interest share shrinking and the principal share growing as the balance goes down.
Formula: payment = loan amount × monthly rate ÷ (1 − (1 + monthly rate)^−number of payments), where monthly rate = APR ÷ 12.
Worked example
A $20,000 loan at 9% APR for 48 months comes out to about $497.70 a month, with $3,889.61 in total interest over the life of the loan (total paid: $23,889.61).
Frequently asked questions
What's the difference between APR and interest rate?
The interest rate is the cost of borrowing the principal. APR (annual percentage rate) is meant to also fold in certain fees, so it's usually a little higher. This calculator treats the number you enter as the rate used to compute interest each month.
Why does my total interest look so high?
Interest compounds on whatever you still owe. Longer terms and higher rates both increase total interest, even if the monthly payment feels more manageable.
Does paying extra each month help?
Yes: extra payments go straight to principal, which shrinks future interest. This version shows the standard scheduled payment only.
Can I use this for a student loan?
Yes, for a fixed-rate loan with a standard amortization schedule. Income-driven repayment plans and loans with changing rates work differently and aren't modeled here.
Assumptions & sources
- Fixed interest rate and fixed monthly payment for the full term (no variable-rate modeling).
- No origination fees or other charges included unless you fold them into the loan amount yourself.
- Standard amortization formula, the same one used by the Consumer Financial Protection Bureau's loan calculators (consumerfinance.gov).
Educational estimates, not financial advice.