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Simple Interest Calculator

Math

Compute simple (non-compounding) interest and total payoff from principal, annual rate, and term

Enter a principal, an annual interest rate, and a term in years to compute simple interest using the flat, non-compounding formula: interest equals principal times rate times time. Unlike the Compound Interest Calculator, interest here is never reinvested, so the growth is linear rather than exponential, matching how short-term loans, promissory notes, and many bonds actually accrue interest. The term accepts fractional years, so a six-month note can be entered as 0.5. Everything is computed from the formula you supply, not a live rate feed, and nothing is sent anywhere in the browser tool.

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How to use Simple Interest Calculator

  • 1.Enter a principal, annual interest rate, and term in years (fractional years like 0.5 for six months are supported).
  • 2.Read off the interest earned and the total payoff (principal plus interest).
  • 3.Use the sample buttons to see a short-term and a multi-year example side by side.

Frequently asked questions

How is this different from the Compound Interest Calculator?
Simple interest is a flat percentage of the original principal each year, with nothing reinvested. Compound interest reinvests the interest earned each period, so it grows faster over time for the same rate.
Can I enter a term shorter than a year?
Yes, the years field accepts decimals, so a 6-month term is 0.5 and a 90-day term is roughly 0.25.
Does this account for taxes or fees?
No. It computes the standard simple-interest formula over the numbers you supply, with no jurisdiction-specific tax or fee logic layered on top.
Is my data sent anywhere?
No, the browser tool computes everything client-side. The REST API and SDKs process whatever numbers you send them, same as any other API call.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/simple-interest-calculator \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"principal":1000,"annualRatePercent":5,"years":2}'

Get an API key from your dashboard · Full API docs →

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