How is simple interest different from compound?

Simple interest is charged only on the original principal, whereas compound interest also earns on accumulated interest.

Where is simple interest used?

Short-term loans, some bonds and basic savings promotions often use simple rather than compound interest.

Simple Interest Calculator

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Principal ($)

Annual rate (%)

Years

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Calculate simple interest that accrues only on the original principal, not on prior interest. Free.

How to use Simple Interest Calculator

Open the toolNo signup and nothing to install; it works as soon as the page loads.
Set “Principal”
Set “Annual rate”
Set “Years”
Read the resultChange any input and the result is recalculated immediately.

Worked example with the defaults

SIMPLE INTEREST · $1,150 total after 3 years: $150.00

Nothing you enter leaves your device

All of the work happens inside your browser. Whatever you type is never packaged up and sent to a server, and no request this page makes carries it.

That makes it safe for contract amounts, personal details and internal documents you would rather not hand to a third party — close the tab and it is gone.

What this tool does not do

Simple Interest Calculator only does what a browser can do on its own — it talks to no backend service. So it keeps no history for you and syncs nothing across devices; if you need a record, copy or download the result.

It is also not a substitute for professional judgement. For legal, medical or tax decisions, treat the output as a starting point rather than a final answer.

Frequently Asked Questions

How is simple interest different from compound?: Simple interest is charged only on the original principal, whereas compound interest also earns on accumulated interest.
Where is simple interest used?: Short-term loans, some bonds and basic savings promotions often use simple rather than compound interest.