See how your investments could grow. This free investment calculator projects the future value of a lump sum plus regular contributions, showing your total returns, overall ROI, and how much of your ending balance comes from compounding rather than your own money.
Results update automatically as you type. Estimates only — investment returns vary and are not guaranteed.
How the Investment Calculator Works
This investment calculator projects the future value of an initial lump sum plus regular monthly contributions, growing at a compounding annual rate, and reports how much of the ending balance came from your own money versus investment returns.
Formula: Future value FV = P × (1+i)^N + C × [(1+i)^N − 1] / i, where i = Annual return ÷ 12 and N = Years × 12. Total ROI = (FV − Total invested) ÷ Total invested × 100
- P — initial investment
- C — monthly contribution
- i — monthly return rate (annual return ÷ 12)
- N — total number of months invested (years × 12)
- FV — projected future value at the end of the period
Example Scenarios
| Initial Investment | Monthly Contribution | Annual Return | Years | Future Value | Total ROI |
|---|---|---|---|---|---|
| $10,000 | $500 | 8% | 20 | $343,200 | 164% |
| $25,000 | $0 | 7% | 30 | $202,900 | 712% |
| $0 | $300 | 6% | 25 | $207,900 | 131% |
| $50,000 | $1,000 | 9% | 15 | $570,300 | 148% |
| $5,000 | $200 | 10% | 10 | $54,500 | 88% |
Investment Calculator FAQ
What’s the difference between this and the retirement calculator?
Both use the same compound growth math, but this calculator is built for any investment goal, not just retirement, and reports total ROI as a percentage. Use whichever framing matches your question — retirement age and 4%-rule income don’t apply here, so this version is more general-purpose.Does the future value account for taxes on investment gains?
No — the projection is a pre-tax estimate of investment growth. Actual after-tax returns depend on the account type (taxable, tax-deferred like an IRA, or tax-free like a Roth), your holding period and applicable capital gains rates, none of which this calculator factors in.How does ROI here differ from just looking at the future value?
Total ROI expresses your gain as a percentage of what you actually put in (initial investment plus contributions), which makes it easier to compare outcomes across different investment amounts or time periods than comparing raw dollar figures alone.Why does a small change in annual return make such a big difference over time?
Returns compound — each year’s gain earns its own return in later years, so the effect snowballs. Over a couple of decades, even a 1-2 percentage point difference in assumed annual return can change the ending balance by a large margin, which is why it’s worth testing a range of return assumptions.Should I include dividends in my expected annual return?
Yes, if you plan to reinvest them. The annual return field represents your total expected growth rate, so if your investment pays dividends or interest that get reinvested, include that in the return percentage rather than adding it separately.What if I want to model a one-time lump sum with no ongoing contributions?
Leave the monthly contribution field at zero and enter only your initial investment. The calculator will project growth from compounding alone, which is useful for comparing a lump-sum investment against a strategy that spreads the same total amount out over time.Related Calculators
To see the same compounding math applied specifically to retirement planning, check out the retirement calculator. If you want to isolate how compounding alone builds your balance, the compound interest calculator breaks that down, and the ROI calculator can help you evaluate a completed investment’s return.