Free Investment Calculator
Free compound interest calculator with monthly contributions, inflation adjustment, retirement withdrawal planning, and realistic variable returns simulation
Investment Calculator
Forecast your wealth and plan for the future
Configure Investment
PORTFOLIO SUMMARY
| Series | Label | Value | Date |
|---|---|---|---|
| Portfolio Value | Year 0 | $1,000 | Year 0 |
| Portfolio Value | Year 1 | $7,249 | Year 1 |
| Portfolio Value | Year 2 | $13,916 | Year 2 |
| Portfolio Value | Year 3 | $21,031 | Year 3 |
| Portfolio Value | Year 4 | $28,621 | Year 4 |
| Portfolio Value | Year 5 | $36,720 | Year 5 |
| Portfolio Value | Year 6 | $45,361 | Year 6 |
| Portfolio Value | Year 7 | $54,581 | Year 7 |
| Portfolio Value | Year 8 | $64,418 | Year 8 |
| Portfolio Value | Year 9 | $74,915 | Year 9 |
| Portfolio Value | Year 10 | $86,114 | Year 10 |
| Portfolio Value | Year 11 | $98,063 | Year 11 |
| Portfolio Value | Year 12 | $110,812 | Year 12 |
| Portfolio Value | Year 13 | $124,416 | Year 13 |
| Portfolio Value | Year 14 | $138,930 | Year 14 |
| Portfolio Value | Year 15 | $154,417 | Year 15 |
| Portfolio Value | Year 16 | $170,940 | Year 16 |
| Portfolio Value | Year 17 | $188,570 | Year 17 |
| Portfolio Value | Year 18 | $207,381 | Year 18 |
| Portfolio Value | Year 19 | $227,452 | Year 19 |
| Portfolio Value | Year 20 | $248,867 | Year 20 |
| Portfolio Value | Year 21 | $271,716 | Year 21 |
| Portfolio Value | Year 22 | $296,095 | Year 22 |
| Portfolio Value | Year 23 | $322,107 | Year 23 |
| Portfolio Value | Year 24 | $349,862 | Year 24 |
| Portfolio Value | Year 25 | $379,474 | Year 25 |
| Portfolio Value | Year 26 | $411,071 | Year 26 |
| Portfolio Value | Year 27 | $444,783 | Year 27 |
| Portfolio Value | Year 28 | $480,753 | Year 28 |
| Portfolio Value | Year 29 | $519,132 | Year 29 |
| Portfolio Value | Year 30 | $560,081 | Year 30 |
| Total Contributed | Year 0 | $1,000 | Year 0 |
| Total Contributed | Year 1 | $7,000 | Year 1 |
| Total Contributed | Year 2 | $13,000 | Year 2 |
| Total Contributed | Year 3 | $19,000 | Year 3 |
| Total Contributed | Year 4 | $25,000 | Year 4 |
| Total Contributed | Year 5 | $31,000 | Year 5 |
| Total Contributed | Year 6 | $37,000 | Year 6 |
| Total Contributed | Year 7 | $43,000 | Year 7 |
| Total Contributed | Year 8 | $49,000 | Year 8 |
| Total Contributed | Year 9 | $55,000 | Year 9 |
| Total Contributed | Year 10 | $61,000 | Year 10 |
| Total Contributed | Year 11 | $67,000 | Year 11 |
| Total Contributed | Year 12 | $73,000 | Year 12 |
| Total Contributed | Year 13 | $79,000 | Year 13 |
| Total Contributed | Year 14 | $85,000 | Year 14 |
| Total Contributed | Year 15 | $91,000 | Year 15 |
| Total Contributed | Year 16 | $97,000 | Year 16 |
| Total Contributed | Year 17 | $103,000 | Year 17 |
| Total Contributed | Year 18 | $109,000 | Year 18 |
| Total Contributed | Year 19 | $115,000 | Year 19 |
| Total Contributed | Year 20 | $121,000 | Year 20 |
| Total Contributed | Year 21 | $127,000 | Year 21 |
| Total Contributed | Year 22 | $133,000 | Year 22 |
| Total Contributed | Year 23 | $139,000 | Year 23 |
| Total Contributed | Year 24 | $145,000 | Year 24 |
| Total Contributed | Year 25 | $151,000 | Year 25 |
| Total Contributed | Year 26 | $157,000 | Year 26 |
| Total Contributed | Year 27 | $163,000 | Year 27 |
| Total Contributed | Year 28 | $169,000 | Year 28 |
| Total Contributed | Year 29 | $175,000 | Year 29 |
| Total Contributed | Year 30 | $181,000 | Year 30 |
Advanced Breakdown - Full Journey
Complete year-by-year breakdown for all 30 years with detailed metrics
How Compound Interest Works
Compound interest is the secret behind long-term wealth building. Unlike simple interest that only earns on your initial investment, compound interest earns returns on both your principal and your accumulated interest. This creates a snowball effect where your money grows exponentially over time.
For example, $10,000 invested at 7% annually becomes $19,672 after 10 years with compound interest. That is nearly double your money without adding a single dollar. Use our compound interest calculator with monthly contributions to see how regular investing accelerates your growth dramatically.
Key Features of This Calculator
- Variable Returns Simulation: Real markets don't return a steady 7% every year. Our variable returns feature models realistic market volatility so you can see how your portfolio might perform through ups and downs.
- Retirement Withdrawal Planning: Planning to retire? Our retirement withdrawal calculator lets you schedule monthly withdrawals starting at any year, shows when your portfolio might be depleted, and helps you plan sustainable withdrawal rates.
- Contribution Adjustments: Life changes. Increase your contributions when you get a raise, or decrease them during career transitions. Model your real financial journey.
- Inflation Adjustment: Our investment calculator with inflation shows your future portfolio value in today's dollars. A million dollars in 30 years won't buy what it does today.
- Fee Impact Analysis: Even small fees compound over time. See exactly how much you're paying in investment fees over your time horizon.
Smart Investing Tips
Start Early
Time is your biggest advantage. Starting 10 years earlier can double your retirement savings even with smaller contributions.
Stay Consistent
Regular monthly contributions through market ups and downs (dollar-cost averaging) reduces risk and builds wealth steadily.
Minimize Fees
A 1% fee difference can cost you hundreds of thousands over 30 years. Choose low-cost index funds when possible.
Stay the Course
Market volatility is normal. Historically, staying invested through downturns has rewarded patient investors.
About Our Maths
This calculator uses the standard compound interest formula with monthly compounding: FV = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) - 1) / (r/n)], where FV is future value, P is principal, r is annual rate, n is compounding periods per year, t is time in years, and PMT is the periodic payment.
When variable returns are enabled, we simulate realistic market behavior using a momentum-based model. Rather than generating purely random returns each year, the simulation accounts for trailing effects: a market down 30% one year is unlikely to suddenly return 12% the next. Each year's return is influenced by the previous year's performance, creating more realistic sequences of bull and bear market periods. The volatility setting controls how much variation exists around your expected return.
Inflation adjustment converts future values to present-day purchasing power using the formula: Real Value = Nominal Value / (1 + inflation)^years. This helps you understand what your future portfolio will actually be worth in terms of what you can buy today.
Fee calculations assume annual expense ratios that compound over time, showing you the true cost of investment fees on your long-term wealth accumulation.
Understanding Market Returns
The S&P 500 has delivered an average annual return of approximately 10% before inflation (about 7% after inflation) over the past century. However, this average masks significant year-to-year variation. In any given year, returns can range from -40% to +50%.
Different asset classes have different risk and return profiles. Bonds typically offer lower returns (3-5% historically) with less volatility. International stocks and emerging markets may offer higher potential returns but with increased risk. Real estate and REITs provide another avenue for diversification.
The 7% return commonly used in retirement planning is a conservative estimate that accounts for inflation. More aggressive portfolios might target 8-10%, while conservative portfolios might aim for 4-6%. Your appropriate target depends on your age, risk tolerance, and investment timeline.
A note on behavioral finance: These projections assume you stay invested and never react emotionally to market swings. In reality, watching your portfolio drop 30% for three consecutive years can trigger panic selling or impulsive rebalancing at the worst possible time. Studies show that investors who try to time the market consistently underperform those who stay the course. This is why matching your portfolio to your true risk tolerance matters: if a 40% drop would keep you up at night, a more conservative allocation may deliver better real-world returns than an aggressive one you abandon during a crash.
Remember: past performance is not indicative of future results. Future returns may differ significantly from historical averages due to changing economic conditions, interest rates, and global factors.
Ready for More Powerful Planning?
This calculator shows one scenario at a time. FinPal runs tens of thousands of Monte Carlo simulations to show you the full range of possible outcomes, plus goal-based planning and personalized roadmaps that reveal exactly how your decisions today impact your retirement tomorrow.
Disclaimer: This calculator is for educational purposes only and does not constitute financial advice. Past performance does not guarantee future results. Consult a qualified financial advisor for personalized investment guidance.