Loan Calculator
How loan payments are calculated
Use this calculator for a fixed-rate installment loan with equal monthly payments. It estimates the payment, total paid, and total interest from the principal, annual percentage rate, and number of months.
Formula and method
Payment = P × [r(1+r)^n] ÷ [(1+r)^n − 1]. For a 0% loan, payment equals principal divided by the number of months.
Worked example
A $25,000 loan at 5.5% for 60 months has a payment of about $478 per month before fees.
How to interpret the result
Use the payment, total paid, and total interest together. A longer term usually lowers the monthly payment while increasing lifetime interest. The calculation assumes one fixed rate and evenly spaced monthly payments, so it fits conventional installment loans better than credit cards, variable-rate debt, or loans with balloon payments.
Important limitations
- Origination fees and optional products are not included.
- Actual APR and payment timing may change lender results.
Common questions
Is the entered rate the same as APR?
APR can include certain finance charges in addition to interest. If a lender's APR includes fees that are not added to the principal here, this calculator will not reproduce the disclosure exactly.
What happens at a zero-percent rate?
The principal is divided evenly by the number of months. Any origination fee or required add-on product still raises the real cost even if the stated interest rate is zero.
Source and further reading
CFPB: What is an interest rate?
Related tools
Method and examples reviewed September 8, 2026.