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Compound Interest

Projects how savings grow from compound interest plus regular contributions.

Result
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How to use it

  • Enter Starting amount.
  • Enter Annual rate %.
  • Enter Years.
  • Enter Compounds / year.
  • Enter Monthly contribution.

The formula

A = P(1+r/n)โฟแต— + PMTยท[((1+r/n)โฟแต—โˆ’1)/(r/n)]

Worked example

$10,000 at 7% for 20 years with $200/month grows to roughly $148,000.

Frequently asked questions

What is compounding?

Earning returns on past returns, not just the starting sum.

Does frequency matter?

More frequent compounding raises the result slightly.

Tips

  • Time in the market beats timing the market.
  • Reinvest returns to let compounding work.
  • Keep fees low โ€” they compound against you.

Key terms

Compounding
Earning returns on past returns.
CAGR
The smoothed annual growth rate.
Yield
Income as a percent of price.