Compound growth

What that becomes. Time does the heavy lifting.

The plain compound-interest projection. Plug in what you can save each month, how long, and a return assumption. The chart shows the compounded balance against the raw cash you put in — the gap is the compounding upside, and it's the whole reason starting earlier beats earning more.

Monthly contribution
$
Starting balance
$

Optional — start from $0 if you're just beginning.

Years
yr
Annual return rate
%

7% is the long-run nominal stock-market average. Adjust if you have a reason.

What your numbers say

The math

Future value of an ordinary annuity: FV = PMT × ((1+r)ⁿ − 1) / r, plus FV of a lump sum if you start with a balance.

Annual compounding, contributions assumed at end of each year. Same convention as the 401(k), Roth, and negotiation calculators — the cross-tool numbers stay consistent.

Want to talk through whether the rate is realistic?

$500/mo is the easy part. The hard part is whether it actually fits your life.

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