Interest Calculator (Simple & Compound)
Switch between simple and compound interest to see how your money or debt grows over time.
About this calculator
Simple interest is charged only on the principal; compound interest is charged on principal plus accumulated interest, so it grows faster.
Toggle the mode to compare both on the same inputs.
All calculations happen in your browser — your numbers are never sent anywhere. Results are estimates for guidance only, not financial advice.
Frequently asked questions
What's the difference between simple and compound interest?
Simple interest applies only to the principal each period; compound interest also applies to previously earned interest.
Which do banks use?
Most loans and deposits use compound interest; some short-term products use simple interest.
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