Investment growth calculator
Model how a lump sum or regular contributions grow over time. Compare strategies and see the impact of different return assumptions.
What is an investment growth calculator?
An investment calculator models how an initial deposit and ongoing monthly contributions could compound over time, given an expected return and fund fees. It's the same math underlying every retirement projection — pared down so you can see exactly which inputs matter most.
The full breakdown.
| Year | Contributed | Gains | Portfolio value | Gains share |
|---|---|---|---|---|
| Y01 | $28,600 | $2,210 | $30,810 | 7% |
| Y02 | $32,200 | $4,902 | $37,102 | 13% |
| Y03 | $35,800 | $8,117 | $43,917 | 18% |
| Y04 | $39,400 | $11,897 | $51,297 | 23% |
| Y05 | $43,000 | $16,289 | $59,289 | 27% |
| Y06 | $46,600 | $21,345 | $67,945 | 31% |
| Y07 | $50,200 | $27,120 | $77,320 | 35% |
| Y08 | $53,800 | $33,672 | $87,472 | 38% |
| Y09 | $57,400 | $41,067 | $98,467 | 42% |
| Y10 | $61,000 | $49,375 | $110,375 | 45% |
| Y11 | $64,600 | $58,671 | $123,271 | 48% |
| Y12 | $68,200 | $69,037 | $137,237 | 50% |
| Y13 | $71,800 | $80,563 | $152,363 | 53% |
| Y14 | $75,400 | $93,344 | $168,744 | 55% |
| Y15 | $79,000 | $107,485 | $186,485 | 58% |
| Y16 | $82,600 | $123,098 | $205,698 | 60% |
| Y17 | $86,200 | $140,305 | $226,505 | 62% |
| Y18 | $89,800 | $159,240 | $249,040 | 64% |
| Y19 | $93,400 | $180,045 | $273,445 | 66% |
| Y20 | $97,000 | $202,876 | $299,876 | 68% |
The future value formula powering the projection.
The calculator combines two effects: compound growth on your existing balance, and the accumulated value of each regular contribution you make. Together they produce the future value shown in the chart.
The key insight is that both components grow exponentially. Money invested earlier has more time to compound, which is why increasing contributions — or starting sooner — has an outsized effect in later years.
- FV
- Future value — projected portfolio balance at end of period
- PV
- Present value — your initial lump-sum investment today
- r
- Rate per period — annual return divided by compounding periods per year
- t
- Periods — total number of compounding periods
- PMT
- Contribution — amount added each period (monthly, annual, etc.)
Six ways to actually use these numbers.
Use 6-7% real, not 10% nominal.
The S&P's nominal long-run return is ~10%, but 2-3% of that gets eaten by inflation. Plan in real dollars.
Stay invested through the chop.
Missing the 10 best market days of a decade can cut your return by 50%+. The hard part of investing is doing nothing.
Fees of 1% = 30% of your money.
Over 40 years at 7% returns, a 1% fee swap-out (active to passive) typically grows your final balance by 25-30%.
Maximize tax-advantaged space first.
401(k) match → HSA → Roth IRA → 401(k) max → taxable. The calculator works for all accounts; the wrapper matters.
Rebalance once a year.
Drifted to 80/20 stocks/bonds from a 70/30 target? Trim back. Forces buy-low/sell-high without market-timing.
Set it and forget it.
Automate the monthly contribution from your paycheck. The friction of manually transferring kills more portfolios than market crashes do.