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Simple interest calculator

See how much an amount earns with simple interest, adding deposits every month. Compare it right away with what compound interest would give you.

With simple interest, interest is charged only on the amount invested, never on earlier interest.

Calculate interest To see the result, you watch a short ad. No data is saved.
Your result shows up here Fill in the fields and tap Calculate interest.

How we calculate

With simple interest, each amount invested earns the same sum every month, calculated on itself. Monthly deposits start earning the month after they go in.

Interest = Principal × i × n

i = monthly rate (yearly rate ÷ 12) · n = months. For comparison, we also calculate the same scenario with compound interest.

Frequently asked questions

How is it different from compound interest?

With compound interest, each month’s interest starts earning too. Over long periods the difference gets big.

Where is simple interest used?

In some short-term loans, late fees and penalties. Most investments use compound interest.

Can I use only years or only months?

Yes. Fill in one field and leave the other at 0.

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