Saving & Investing
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Compound Interest Calculator

Compounding is interest earning interest. Set a starting balance, a monthly contribution and a rate to watch your money grow — and see how much of the result is pure growth.

Your numbers
$
$
7%
25 yrs
Over time

Use Left and Right Arrow, Home, or End to inspect data points.

$272k$136k$001225
BalanceContributions

Estimates only — not financial advice. They produce estimates based on the figures you enter and do not account for every fee, tax or change in rate.

Sources & assumptions

Formula 2026.07.18
Page updated 2026-07-18

Read the full methodology
  • The result is a deterministic estimate from the inputs shown on this page.
  • Fees, taxes and real-world terms not represented by an input are excluded.
  • Confirm material decisions against original documents or a qualified professional.
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Why time matters more than amount

Because growth compounds, money invested early has decades to multiply. Starting ten years sooner often beats contributing much more later. The shaded gap between contributions and balance above is compounding at work — and it widens fastest in the final years.

Frequently asked questions