Free Investment Calculator
Calculate your investment growth with compound interest and regular contributions. See how your money grows over time with year-by-year projections.
Investment Details
S&P 500 avg: ~10%
Final Balance
After 20 years with monthly compounding
Total Contributions
$130,000
Total Interest Earned
$172,370
Monthly Investment
$500
Annual Return
7%
Total Years
20
Interest Ratio
57.0%
Year-by-Year Growth
| Year | Start Balance | Contributions | Interest | End Balance |
|---|---|---|---|---|
| Year 1 | $10,000 | +$6,000 | +$955 | $16,955 |
| Year 2 | $16,955 | +$6,000 | +$1,458 | $24,413 |
| Year 3 | $24,413 | +$6,000 | +$1,997 | $32,411 |
| Year 4 | $32,411 | +$6,000 | +$2,575 | $40,986 |
| Year 5 | $40,986 | +$6,000 | +$3,195 | $50,182 |
| Year 6 | $50,182 | +$6,000 | +$3,860 | $60,042 |
| Year 7 | $60,042 | +$6,000 | +$4,573 | $70,614 |
| Year 8 | $70,614 | +$6,000 | +$5,337 | $81,952 |
| Year 9 | $81,952 | +$6,000 | +$6,157 | $94,108 |
| Year 10 | $94,108 | +$6,000 | +$7,036 | $107,144 |
| Year 11 | $107,144 | +$6,000 | +$7,978 | $121,122 |
| Year 12 | $121,122 | +$6,000 | +$8,988 | $136,110 |
| Year 13 | $136,110 | +$6,000 | +$10,072 | $152,182 |
| Year 14 | $152,182 | +$6,000 | +$11,234 | $169,416 |
| Year 15 | $169,416 | +$6,000 | +$12,480 | $187,895 |
| Year 16 | $187,895 | +$6,000 | +$13,815 | $207,710 |
| Year 17 | $207,710 | +$6,000 | +$15,248 | $228,958 |
| Year 18 | $228,958 | +$6,000 | +$16,784 | $251,742 |
| Year 19 | $251,742 | +$6,000 | +$18,431 | $276,173 |
| Year 20 | $276,173 | +$6,000 | +$20,197 | $302,370 |
Quick Scenarios
Investment Tips:
- The S&P 500 has historically returned ~10% annually before inflation
- Time in the market beats timing the market - start early
- More frequent compounding slightly increases returns
- Consider tax-advantaged accounts (401k, IRA) for long-term investing
- This calculator shows nominal returns - adjust for inflation (2-3%) for real returns
How to Use the Investment Calculator
Enter Your Starting Investment
Input your initial investment amount - the lump sum you plan to invest today. This becomes the principal that will grow through compound interest over time.
Set Monthly Contributions
Enter how much you plan to invest each month on a regular basis. Consistent contributions through dollar-cost averaging can significantly boost your long-term returns.
Choose Return Rate and Time Period
Enter your expected annual return rate (historically 7-10% for stock market) and the number of years you plan to invest. Select your preferred compounding frequency.
Analyze Your Investment Growth
View your projected final balance, total contributions, and interest earned. Review the year-by-year breakdown to see how your wealth builds over time through compound growth.
Pro tip: Your data is processed entirely in your browser. Nothing is sent to any server, ensuring complete privacy.
The Power of Long-Term Investing
Long-term investing harnesses the power of compound growth to build wealth over time. The earlier you start and the more consistently you invest, the greater your potential returns. Time in the market typically beats timing the market.
Investment Strategies
- Dollar-Cost Averaging: Invest regularly regardless of market conditions
- Diversification: Spread investments across asset classes
- Rebalancing: Periodically adjust portfolio allocations
- Tax Efficiency: Use 401(k) and IRA accounts
- Long-Term Focus: Ignore short-term volatility
Frequently Asked Questions
How do I calculate compound interest on investments?
Compound interest is calculated using the formula A = P(1 + r/n)^(nt) where P is principal, r is annual rate, n is compounding frequency, and t is time. Our calculator handles this automatically and also factors in regular contributions.
What is a good annual return rate to expect?
Historically, the S&P 500 has returned about 10% annually before inflation (7% after inflation). Conservative bond portfolios return 4-6%, while aggressive stock portfolios may target 10-12%. Use 7% for conservative long-term projections.
How often should my investments compound?
Most investments compound daily or monthly. More frequent compounding yields slightly higher returns. For example, 7% compounded daily vs annually creates about 0.25% more growth per year.
What is the power of compounding?
Compounding means earning returns on your returns. Over time, this creates exponential growth. $10,000 invested at 7% for 30 years becomes $76,000 without contributions. With $500/month contributions, it grows to over $680,000.
Should I invest monthly or annually?
Monthly investing (dollar-cost averaging) is generally better because you buy at various price points, reducing timing risk. It also allows more of your money to work for you earlier.
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