✓ Effortless Math · Free Tool

Simple & Compound Interest Calculator

Enter your principal, annual rate, and time — choose simple or compound interest — to instantly get the final amount, interest earned, growth factor, and a live balance graph, with full step-by-step working.

Simple:  I = P·r·t  ·  Compound:  A = P·(1 + r/n)n·t
Principal P ($) Rate r (%) Time t (years) Mode Compounded

Enter r as a percent (e.g. 5 means 5%). Choose Compound to pick how often it compounds per year.

Results

Final amount (A)
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Interest earned (I)
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Principal (P)
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Growth factor (A/P)
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Graph — balance over time

BalancePrincipalFinal amount

Step-by-step