Compound interest · Free calculator
Compound Interest Calculator
See how your savings grow over time — with interest earning interest. Adjust the inputs below and watch your money compound in real time.
Your numbers
$
$0$500k
$
$0$5k/mo
%
0%20%
yrs
0 yrs50 yrs
Compounds
Final balance
—
Total contributed
—
Interest earned
—
Growth breakdown —
Contributions Interest earned
Year-by-year growth
| Year | Balance | Contributed | Interest |
|---|
Why compounding is powerful
Compounding means your interest earns interest. At 7% annually, money doesn't just grow — it accelerates. $10,000 becomes $19,671 in 10 years without adding a single dollar. Add $500/month and it becomes $97,656.
The single biggest lever is time. Starting 10 years earlier can more than double your final balance — far more than doubling your contribution rate.
What rate should you expect?
- ~4–5% — High-yield savings account or CDs (2024 rates)
- ~7% — Historical S&P 500 average return (inflation-adjusted)
- ~10% — Historical S&P 500 nominal average
- >12% — Possible with individual stocks; carries higher risk
Past returns don't guarantee future results.
Also try