Interest Calculator
Compute simple interest on a principal over time.
This is simple interest (I = P × r × t), not compound interest. For interest that compounds over time, use the compound interest calculator instead.
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Frequently asked questions
Simple interest only. Interest is computed once on the original principal: I = P × r × t. If you need interest that earns interest, use the compound interest calculator.
Short-term personal loans, some bonds, and quick mental-math estimates. Most savings accounts, mortgages, and credit cards use compound interest, so reach for the compound interest calculator instead.
No. The result is the gross interest earned. Subtract any platform fees and the tax rate that applies to interest income for a net figure.
Last updated 2026-06-03.