Last updated: March 2026
How the Investment Calculator Works
This investment calculator uses monthly compounding to project how your money grows over time. Each month, your current balance earns returns at your specified rate, and your monthly contribution is added to the total. This mirrors how most real investment accounts work — 401(k)s, IRAs, and brokerage accounts all compound regularly.
The calculator shows four key metrics: future value (your projected total), total contributed (money you put in), investment growth (returns earned), and return multiple (how many times your contributions have multiplied). Together, these paint a complete picture of your investment outcome.
Choose from five preset investment profiles — from conservative bonds at 5% to historical S&P 500 returns at 10.5% — or enter any custom return rate. The comparison table lets you see all profiles side by side at 10, 20, and 30 year marks, making it easy to understand the long-term impact of your investment strategy.
The "What If" insights section automatically calculates how starting earlier, contributing more, or earning a higher return would change your outcome. These personalized insights help you identify the highest-impact changes you can make to your investment plan.
Frequently Asked Questions
How do I calculate my investment returns?
Enter your starting investment amount, monthly contribution, expected annual return rate, and time horizon. The calculator uses monthly compounding to project your balance year by year, showing both your total contributions and investment growth separately.
What is a good annual return for investments?
It depends on your investment type. Savings accounts and CDs offer 4-5%, bonds 3-5%, a balanced portfolio around 7%, and the S&P 500 has historically averaged 10.5% before inflation. Use the preset profiles to compare different strategies.
Should I adjust for inflation?
Yes, especially for long-term projections. Inflation averaging 3% per year means $100,000 in 20 years will only buy what roughly $55,000 buys today. Enable the inflation toggle to see your investment's future purchasing power in today's dollars.
How much should I invest per month?
Financial advisors commonly recommend saving 15-20% of your income for retirement. Even small amounts matter — $200 per month at 7% for 30 years grows to over $240,000. Use this calculator to find the monthly contribution that meets your goals.
Is this calculator accurate for real investments?
This calculator provides useful projections based on a constant return rate. Real investments experience variable returns, fees, taxes, and market volatility. Use these projections as a planning tool and consult a financial advisor for personalized advice.