Interest rate calculator
Solve for a simple annual rate when you know the interest amount.
Formula
Annual rate (%) = interest / (principal × years) × 100
Simple annual interest rate ≈ (660)÷(3,000)÷(4)×100
How to use
- Enter principal and the total interest earned or paid.
- Enter the term in years, greater than zero.
- Read the implied simple annual percentage rate.
Examples
- 660 interest on 3,000 over 4 years implies 5.5% a year.
- 25 interest on 1,000 over half a year implies 5% a year.
Frequently asked questions
What interest amount should I enter?
Only interest, excluding the original principal and any separate fees.
Is this APR or APY?
No. It solves I = P × r × t without fees, repayments or compounding.
What if the balance changes?
This model assumes unchanged principal; it does not solve an amortizing loan rate.
Sources
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