Finance tool

Simple Interest Calculator

Interest, principal, rate or time with I = PRT.

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–Interest
–Total (principal + interest)

About this tool

Simple Interest Calculator uses I = P × R × T to find the interest on a loan or deposit that does not compound. It can also work backwards to find the principal, rate or time you need for a given amount of interest.

How to use Simple Interest Calculator

  1. Choose what to solve for.
  2. Fill in the other values.
  3. Read the result and the working.

Questions people ask

What is the simple interest formula?

I = P × R × T, where P is the principal, R the yearly rate as a decimal and T the time in years. 5,000 at 4% for 3 years earns 5,000 × 0.04 × 3 = 600, for a total of 5,600.

How do I rearrange it to find rate or time?

P = I ÷ (R × T), R = I ÷ (P × T) and T = I ÷ (P × R). Time from months is months ÷ 12 and from days is days ÷ 365.

How is simple interest different from compound interest?

Simple interest is charged only on the original principal. Compound interest is also charged on interest already added. Over 3 years at 4%, 5,000 earns 600 simple but 624.32 compounded yearly.

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