Investment Calculator
Project investment growth with monthly or annual contributions, compare return rates, and see inflation-adjusted results
Two things drive how much an investment grows: how long it's invested, and how much goes in along the way. This calculator separates the two so you can see, in dollars, how much of your final balance is money you actually put in versus money the market grew for you, and lets you compare that across return-rate scenarios or track it year by year.
Your initial $10,000 alone would grow to about $38,697. The rest of the final balance, about $253,768, comes from your recurring contributions and the returns they earn.
| Year | Contributed | Earnings | Balance | In today's $ |
|---|---|---|---|---|
| 1 | $16,000 | $890 | $16,890 | $16,478 |
| 2 | $22,000 | $2,263 | $24,263 | $23,093 |
| 3 | $28,000 | $4,151 | $32,151 | $29,856 |
| 4 | $34,000 | $6,592 | $40,592 | $36,774 |
| 5 | $40,000 | $9,623 | $49,623 | $43,860 |
| 6 | $46,000 | $13,287 | $59,287 | $51,123 |
| 7 | $52,000 | $17,627 | $69,627 | $58,575 |
| 8 | $58,000 | $22,692 | $80,692 | $66,227 |
| 9 | $64,000 | $28,530 | $92,530 | $74,091 |
| 10 | $70,000 | $35,197 | $105,197 | $82,180 |
| 11 | $76,000 | $42,751 | $118,751 | $90,506 |
| 12 | $82,000 | $51,254 | $133,254 | $99,082 |
| 13 | $88,000 | $60,772 | $148,772 | $107,922 |
| 14 | $94,000 | $71,376 | $165,376 | $117,041 |
| 15 | $100,000 | $83,143 | $183,143 | $126,454 |
| 16 | $106,000 | $96,153 | $202,153 | $136,175 |
| 17 | $112,000 | $110,494 | $222,494 | $146,222 |
| 18 | $118,000 | $126,258 | $244,258 | $156,610 |
| 19 | $124,000 | $143,547 | $267,547 | $167,358 |
| 20 | $130,000 | $162,465 | $292,465 | $178,483 |
What Affects Investment Growth
Initial Investment
Your starting amount compounds for the entire period, so it tends to matter more the longer the time horizon is.
Contribution Amount & Frequency
Regular contributions do two jobs: they add to what you've put in, and every contribution then earns returns for the rest of the period. Over long periods this is often the largest driver of the final balance.
Annual Return
Long-term returns depend heavily on what you invest in, and results in any single year can be far above or below any average. Use Compare Return Rates to see how sensitive your result is to this one assumption.
Investment Period
Time is where compounding does its work. Starting a decade earlier with the same monthly contribution usually adds far more to the final balance than the extra contributions alone, because the earlier money has more time to grow. Example 2 below shows this directly.
Inflation
A balance that looks large in future dollars buys less than the same number does today. The inflation-adjusted value in the table above divides the future balance by cumulative inflation, showing today's purchasing power rather than the raw future number.
Worked Examples
$10,000 invested with $500 added monthly at a 7% annual return grows to about $292,465 after 20 years. Of that, $130,000 came from contributions and $162,465 came from investment growth, meaning growth accounts for more of the balance than the money actually put in.
The same $10,000 and $500 a month, but invested for 30 years instead of 20, grows to about $660,849. The extra 10 years added $60,000 in additional contributions but $368,384 to the final balance, meaning roughly $308,384 of that increase came from growth alone, not from money put in.
Keeping the 20-year period and 7% return but raising the contribution from $500 to $1,000 a month brings the balance to about $546,233, nearly double Example 1's result, since both the contributions and the growth on those contributions scale up together.
- The annual return is treated as an effective annual rate: with no contributions, your balance grows by exactly that percentage over 12 months.
- Growth is applied month by month at the equivalent monthly rate. Contributions are added at the end of each month or year.
- Inflation-adjusted value = balance ÷ (1 + inflation)^years, shown in today's purchasing power.
- Taxes, fees, and changes in contributions over time are not included.
For interest that compounds at a stated rate on a set schedule, see the Compound Interest Calculator. This tool is for general information only, not financial advice.