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Simple Interest Calculator

In short

Calculate simple interest on a principal from the rate and time, with a yearly breakdown and chart. Runs in your browser, no sign-up.

  • Runs in your browser
  • Nothing uploaded
  • Free, no sign-up

Work out the simple interest on a loan or deposit, where interest is charged only on the original principal. Enter the amount, rate and time to see the interest and final balance. Runs in your browser.

$0total interest
$0final balance
$0interest / month
Final balance with interest$0

Loading chart...

YearInterestCumulativeBalance

Simple interest applies the rate to the original principal only, so it does not compound. For interest that earns interest, use a compound interest calculator instead.

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100% PrivateNo server uploads, ever
InstantRuns in your browser
💧
No WatermarksClean output, always
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Free ForeverNo accounts, no limits

How to Use Simple Interest Calculator

Simple Interest Calculator preview
Simple Interest Calculator. Free online tool that runs in your browser.
  1. Enter the principal. Type the starting amount, the sum you deposit or borrow.
  2. Set the rate and time. Add the annual interest rate as a percent and the length in years.
  3. Read the interest and total. See the interest earned or owed and the final balance, plus a year by year table.
  4. Compare scenarios. Change the rate or time to see how each affects the interest.

Frequently Asked Questions

What is simple interest?

Simple interest is charged only on the original principal, using the formula interest equals principal times rate times time. It does not earn interest on interest.

How is it different from compound interest?

Compound interest adds earned interest back to the balance so future interest is larger. Simple interest stays flat each period, so it grows in a straight line.

When is simple interest used?

It is common on some car loans, short term personal loans and certain bonds. Many savings accounts and mortgages use compound interest instead.

Can I enter a partial year?

Yes. You can use decimals such as 2.5 years, and the interest scales proportionally.

Is my data uploaded?

No. The calculation is pure arithmetic done in your browser.

What does the final balance mean?

It is the principal plus the total interest over the period, which is what you would repay or withdraw.

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