Compound Interest Calculator

Visualize the power of compound growth on your investments

Investment Details

Final Balance

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Total Contributions

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Total Interest Earned

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Rule of 72

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to double at {{ interestRate }}%

Principal vs Interest Breakdown

Year Starting Balance Contributions Interest Earned Ending Balance
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Understanding Compound Interest

Compound interest is often called the "eighth wonder of the world" because of its powerful effect on wealth building. Unlike simple interest, which only earns interest on your initial principal, compound interest earns interest on both your principal AND your previously earned interest.

The Compound Interest Formula

A = P(1 + r/n)^(nt)
  • A = Final amount
  • P = Principal (initial investment)
  • r = Annual interest rate (decimal)
  • n = Number of times interest compounds per year
  • t = Time in years

The Rule of 72

A quick way to estimate how long it takes for your money to double: divide 72 by your annual interest rate. For example, at 8% annual returns, your money doubles approximately every 9 years (72 ÷ 8 = 9).