Free Investment Calculator
Compound Interest Calculator
Plan your financial future with our free compound interest calculator. See how your investments grow over time, compare different starting ages, and visualize your path to retirement.
How This Investment Calculator Works
What is a Compound Interest Calculator?
A compound interest calculator helps you visualize how your investments grow over time through the power of compounding. Unlike simple interest, compound interest earns returns on both your initial investment AND all previously earned interest, creating exponential growth.
How Compound Growth Works
When you invest money, your returns are reinvested to generate additional returns. For example, if you invest $1,000 at 8% annual return, after year one you have $1,080. In year two, you earn 8% on $1,080 (not just $1,000), giving you $1,166.40. This compounding effect accelerates over time, which is why starting early is so powerful.
Understanding Return Rate Assumptions
Our calculator offers several preset return rates based on historical performance: Conservative (~5%) reflects bonds and treasuries, S&P Historic Average (~8%) reflects the long-term S&P 500 performance, Index Funds (~10%) reflects diversified portfolios, and Tech-Focused (~12%) represents higher-risk growth sectors. These are simplified estimates—actual returns vary year to year.
The Power of Starting Early
Our calculator shows you how starting just 1-5 years earlier can result in significantly more wealth at retirement. This visualization helps demonstrate why time in the market is one of the most powerful factors in building wealth. The comparison feature lets you see the exact dollar difference.
US Median Comparison
We compare your projected wealth against the median net worth for Americans at each age, based on Federal Reserve Survey of Consumer Finances (SCF) data. This helps you understand how your investment plan compares to typical wealth accumulation patterns.
Data sources: Historical return assumptions based on long-term market averages. Median net worth data from Federal Reserve Survey of Consumer Finances (2022).
Growth Planning
At age 65
$1,116,613
Put In
$210,000
Interest
+$906,613
Growth
432%
Your Journey
Growth Trajectory
Age
30
Already Invested
$0
Contributing
$500/monthly
Age
65
Total Value
$1,116,613
Total Growth
+432%
Contribute
$210,000
Interest
+$906,613
Final
$1,116,613
Complete Analysis
Investment Breakdown
By investing $500/monthly (or $6,000/year) from age 30 to 65 (35 years) at 8% annual returns, you'll reach:
You'll contribute $210,000 total, earning $906,613 in compound interest. That's a remarkable 432% return.
Wealth Composition
| Type | Amount | % |
|---|---|---|
Contributions | $210,000 | 18.8% |
Interest | $906,613 | 81.2% |
| Total | $1,116,613 | 100% |
The Power of When You Start
Each year makes a significant difference
| Start | Value | Diff |
|---|---|---|
25−5yr | $1,678,686 | +$562,073 |
27−3yr | $1,427,647 | +$311,034 |
29−1yr | $1,212,422 | +$95,809 |
30now | $1,116,613 | — |
31+1yr | $1,027,901 | -$88,712 |
33+3yr | $869,704 | -$246,909 |
35+5yr | $734,075 | -$382,538 |
Key Insights
Let's look at what might happen if you started investing according to three different time frames:
+$95,809
extra at retirement
+173%
above US median
-$88,712
lost opportunity
Important Disclaimers
Not Financial Advice: This calculator is provided for educational and informational purposes only. It does not constitute financial, investment, tax, or legal advice. You should consult with a qualified financial advisor before making any investment decisions.
Estimates Only: All projections and calculations are hypothetical estimates based on the parameters you provide. Actual investment returns will vary and may be significantly different from these projections. Past performance is not indicative of future results.
Market Risk: Investments involve risk, including the potential loss of principal. Market conditions, economic factors, and individual investment performance can significantly impact actual returns. The rates of return used in this calculator are simplified assumptions and do not account for market volatility, inflation, fees, taxes, or other real-world factors.
No Guarantees: We make no representations or warranties regarding the accuracy, completeness, or reliability of the information provided by this calculator. Use at your own risk.
By using this calculator, you acknowledge that you have read and understood these disclaimers and agree that the creators and operators of this tool are not liable for any decisions you make based on the information provided.