Loan interest rate
Loan interest rate: use amount borrowed, monthly payment, number of monthly payments. Review the formula, worked example and calculation steps.
Inputs
Use the units shown—
Enter your values and select Calculate.
Formula & explanation
Solve payment = P r/[1−(1+r)⁻ⁿ]; nominal annual % = 1200r
Variables & units
- Amount borrowed
- currency · minimum 0.01, maximum 1000000000000
- Monthly payment
- currency · minimum 0.01, maximum 1000000000000
- Number of monthly payments
- months · minimum 1, maximum 600
Worked example
10,000 principal, 36 monthly payments of 304.2193745156 implies approximately 6% nominal annual interest.
Assumptions
Not a statutory APR calculation. No fees; supports non-negative monthly rates up to 100%.
Formula version 1.0.0. JavaScript floating-point arithmetic applies. Results display up to 6 decimal places; stored values retain available precision. Use the units shown.
Practice with an example
Use the default input values to find the answer. The reset icon restores those values.
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