Investment Calculator
See how much your investments could grow. Enter a starting amount, a monthly contribution, the number of years and an expected return, and get your future balance, how much of it is growth, what it is worth in today’s dollars and a year-by-year breakdown.
Assumes monthly contributions and monthly compounding, before taxes and fees. Returns are not guaranteed.
| Year | Contributions | Growth | Balance |
|---|
How the investment calculator works
Your balance grows in two ways: the money you add, and the returns your money earns, which then earn returns of their own. That second part is compound growth, and over long periods it usually becomes the larger share.
Example: you start with $10,000 and invest $500 a month for 20 years at a 7% average return. You put in $130,000 in total. Your balance grows to about $300,851, so roughly $170,851 comes from growth. At 3% inflation, that balance would buy about what $166,574 buys today.
Small changes make a big difference. In this example, a 1% higher return adds about $42,900, and investing $100 more each month adds about $52,100.
How much monthly investing can grow
Estimated balance with no starting amount and a 7% average yearly return:
| Monthly | 10 years | 20 years | 30 years | 40 years |
|---|---|---|---|---|
| $100/mo | $17,308 | $52,093 | $121,997 | $262,481 |
| $250/mo | $43,271 | $130,232 | $304,993 | $656,203 |
| $500/mo | $86,542 | $260,463 | $609,985 | $1,312,407 |
| $1,000/mo | $173,085 | $520,927 | $1,219,971 | $2,624,813 |
Time matters more than almost anything else. $250 a month for 40 years grows to more than $500 a month for 30 years, even though you contribute less in total. To see compounding on a single deposit, try the compound interest calculator.
Choosing a rate of return
The return you enter has a huge effect on the result. Here is $500 a month for 30 years ($180,000 contributed) at different average returns:
| Average return | Balance | Growth |
|---|---|---|
| 4% | $347,025 | $167,025 |
| 6% | $502,258 | $322,258 |
| 7% | $609,985 | $429,985 |
| 8% | $745,180 | $565,180 |
| 10% | $1,130,244 | $950,244 |
- 4% to 5%: a cautious estimate for a mix with more bonds and cash.
- 6% to 7%: a common planning rate for a stock-heavy portfolio, roughly in line with long-run stock returns after inflation.
- 8% to 10%: closer to long-run U.S. stock returns before inflation, but with large swings from year to year.
Real returns are never steady. Some years are up 20% or more and others are down sharply. The calculator uses an average so you can plan, not a prediction for any single year.
Fees and taxes: the hidden drag
Fees. A 1% yearly fee sounds small, but it compounds against you. $500 a month for 30 years grows to about $610,000 at 7%, but only about $502,300 at 6%. That 1% costs roughly $107,700. Low-cost index funds often charge 0.1% or less.
Taxes. Where you invest matters as much as what you invest in:
- 401(k): pre-tax contributions and tax-deferred growth, often with an employer match. See the 401(k) calculator.
- Roth IRA: after-tax contributions, but all growth can come out tax-free in retirement. The 2026 limit is $7,500. See the Roth IRA calculator.
- Taxable brokerage account: no contribution limits, but you may owe tax on dividends and on gains when you sell.
A common order is: get the full 401(k) match, then fund a Roth IRA, then go back to the 401(k) or a brokerage account. To see whether your total savings are on track, use the retirement calculator.
Frequently asked questions
How much will I have if I invest $500 a month?
At a 7% average yearly return, $500 a month grows to about $86,500 in 10 years, $260,500 in 20 years and $610,000 in 30 years. You would have contributed $60,000, $120,000 and $180,000. The rest is investment growth. Returns are not guaranteed and change from year to year.
What rate of return should I use?
Many planners use 6% to 7% a year for a stock-heavy portfolio over long periods, after accounting for some inflation, and 4% to 5% for a more conservative mix with bonds. U.S. stocks have historically averaged around 10% a year before inflation over long periods, but with large ups and downs. Using a lower rate gives a more cautious estimate.
How does this calculator handle inflation?
It shows your ending balance in future dollars and, separately, in today's dollars using the inflation rate you enter. At 3% inflation, $1 in 20 years buys about what 55 cents buys today, so the today's-dollars figure is a better guide to what your money will actually buy.
Does the calculator include taxes and fees?
No. It assumes all growth stays invested. In a 401(k) or IRA, growth is tax-deferred or tax-free. In a regular brokerage account, you may owe tax on dividends and gains. To account for fees, lower the return by your fund's expense ratio, for example from 7% to 6.5% for a 0.5% fee.
Is it better to invest a lump sum or monthly?
Historically, investing a lump sum right away has more often come out ahead, because money spends more time in the market. Monthly investing, also called dollar-cost averaging, lowers the risk of investing everything just before a drop and fits how most people get paid. Both work far better than waiting.
This calculator gives estimates for education only and is not investment advice. Investments can lose value, and past returns do not guarantee future results. Results do not include taxes, fees or the timing of market ups and downs.