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Simple Interest Calculator

Estimate interest that is charged only on the original principal rather than on accumulated interest.

How the estimate works

Simple interest equals principal multiplied by annual rate multiplied by time in years.

Important limitation

Most savings accounts and amortizing loans use compounding rather than simple interest. Results are estimates only and are not financial, lending, legal, tax, or investment advice.

Assumptions and review

Formula review: July 29, 2026. This tool uses only the editable values shown above and does not pull live rates, prices, balances, or account data.

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Frequently asked questions

How does the simple interest calculator work?

Simple interest equals principal multiplied by annual rate multiplied by time in years.

Is this simple interest calculator exact?

No. It is a planning estimate based on the values you enter. Actual rates, fees, timing, taxes, and provider rules can change the result.

Can I change the assumptions?

Yes. Every displayed input is editable so you can compare scenarios instead of relying on a hidden default.

Simple Interest Calculator