Investment Return Calculator
Calculate investment growth, total return, ROI, and CAGR with monthly contributions over any time period.
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This calculator shows how your investments grow over time through the power of compound interest. Enter your starting amount, monthly contributions, expected annual return, and time horizon to see your projected portfolio value, total return, ROI, and CAGR.
Example
$10,000 initial investment, $500/month, 7% annual return, 20 years: Final value: ~$284,000 Total contributed: $130,000 Investment growth: ~$154,000 ROI: ~118% CAGR: 7.0%
Formulas
Final value (lump sum) = P × (1 + r/12)^(n×12) Final value (with contributions) = P × (1 + r/12)^(n×12) + C × [((1 + r/12)^(n×12) − 1) / (r/12)] ROI = (Final value − Total contributions) / Total contributions × 100 CAGR = (Final value / Initial amount)^(1/years) − 1
How Compound Interest Works
Compound interest means your returns earn returns. At 7% per year, $10,000 becomes $19,672 in 10 years with no additional contributions — nearly double. Add monthly contributions and the effect multiplies. The earlier you start, the more powerful compounding becomes. A 25-year-old who invests for 10 years and stops often ends up with more than a 35-year-old who invests for 30 years.
Frequently Asked Questions
What annual return rate should I use?
The US stock market (S&P 500) has averaged about 10% nominal / 7% real (after inflation) per year over the long run. For a diversified portfolio, 6–8% is a reasonable conservative assumption.
What is CAGR?
Compound Annual Growth Rate — the steady annual return that would produce the same final value. It smooths out year-to-year volatility into a single comparable number.
Does this account for inflation?
No — this shows nominal (not inflation-adjusted) returns. To get real returns, use a return rate 2–3% lower than nominal (e.g., 5% instead of 7%).
What is the difference between ROI and CAGR?
ROI is total return over the whole period. CAGR is the annualized return rate. For comparing investments over different time horizons, CAGR is more useful.