CompInt

College Savings Compound Calculator

Project a 529-style college fund from monthly saving compounded over 18 years.

Runs locally in your browser — your numbers never leave this page
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Try: Starting principal=1000, Annual interest rate=5, Compounding=12, Years=18, Monthly contribution=150, Annual inflation=0 → $54,835.31, $33,400.00, $21,435.31, $150.00

How to use

Compound interest is interest earned on prior interest. Enter your starting principal, the annual rate, and how often it compounds (daily, monthly, and so on). Add a monthly contribution to model regular saving. The calculator reports the final balance, total interest, and — if you enter inflation — the real purchasing power of that balance.

FAQ

What does compounding frequency change?

More frequent compounding (daily beats annual) gives a slightly higher balance because interest starts earning interest sooner. The difference is small at low rates but grows over long periods.

Why add a monthly contribution?

Regular saving is usually the biggest driver of long-term growth. The calculator treats it as an ordinary annuity added each month.

What is the inflation-adjusted value?

It divides the final balance by (1 + inflation)^years to show what that money could actually buy then, stripping out price rises.

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