Visualize how your investments can grow over time with the power of compound interest
Future Value
$300,851
Total portfolio value
Total Contributions
$130,000
Your invested amount
Interest Earned
$170,851
Growth from interest
Growth Rate
131.4%
Return on investment
Compound interest is interest earned on interest: each period's growth is added to the balance, and the next period's growth is calculated on the new, larger amount. This calculator projects how an initial amount plus regular contributions grows over time at a chosen rate and compounding frequency.
The defining feature of compounding is that growth accelerates. The first years look unremarkable; the later years do most of the work. That's why time in the market — starting early — routinely beats starting later with larger contributions.
A = P(1 + r/n)^(nt)Simple interest is paid only on the original principal, so growth is linear. Compound interest is paid on principal plus accumulated interest, so growth is exponential. Over 30 years at 7%, $10,000 grows to $31,000 with simple interest but over $76,000 with annual compounding.
Less than people expect. $10,000 at 6% for 10 years grows to $17,908 with annual compounding and $18,194 with daily compounding — a difference of under 2%. The rate and the time horizon dominate; frequency is a rounding detail by comparison.
For long-term diversified stock portfolios, 6–8% nominal (before inflation) is a common planning assumption based on historical averages; high-yield savings and bonds are lower. Use conservative numbers for plans you depend on — and remember returns arrive unevenly, not in a straight line.
Early wins surprisingly often. Someone investing $300/month from 25 to 35 and then stopping can end up with more at 65 than someone investing $300/month from 35 to 65, at typical return assumptions — the extra decade of compounding outweighs 20 extra years of contributions.
Why Einstein (allegedly) called compound interest the most powerful force in the universe, and how it can work for — or against — you.