Growth

Compound Interest Calculator

Project how principal and ongoing contributions grow with compounding. Change any assumption and watch the curve update instantly.

Assumptions

Starting principal

$

Contribution

$

Contribution frequency

Annual return

%

Time horizon

yrs

Horizon unit

Compounding

Future value

$302,370.09

After 20 years at 7%

Total contributions
$130,000.00
Interest earned
$172,370.09

Projection

Balance$302.4K
Contributions$130K

Educational estimate only — not financial advice. Markets, taxes, and fees can change outcomes.

FAQ

What is compound interest?: Compound interest means you earn returns on both your original principal and on interest that has already been added. Over long periods, that compounding effect can dominate growth.
Can I model months instead of years?: Yes. Switch the time unit to months for shorter horizons (for example 14 months). The chart then plots monthly progress instead of yearly ticks.
How often should I assume compounding?: Monthly is a common default for brokerage and savings accounts. Annual compounding is simpler and slightly more conservative for rough planning.
Does this include taxes or fees?: No. This is a clean mathematical projection. Real accounts may have fees, taxes, and uneven returns.