Project how an initial investment plus regular monthly contributions could grow over time, including the effect of fees, yearly contribution increases, and inflation.
8% a year is a commonly used long-run average for a diversified stock portfolio before inflation. Actual returns vary year to year, so try several rates.
This tool projects the future value of an initial lump sum plus regular monthly contributions. It follows your portfolio month by month: each month the balance grows at your return, then your contribution is added at the end of the month. That combines two sources of growth, the compounding of your initial investment and the compounding of every contribution from the month it is made until the end of your time horizon.
The return you enter is treated as an annual return, meaning the balance grows by that percentage over a full year, the way investment returns are normally quoted. The calculator converts it to an equivalent monthly rate, so an 8% return grows a lump sum by exactly 8% in a year. Optional inputs refine the projection. Annual fees are subtracted from your return, the contribution increase raises your monthly amount by a percentage each year (for example, to match raises), and the inflation rate converts the final number into today's dollars.
If you only want to project a single lump sum with no ongoing contributions, our Compound Interest Calculator is a simpler tool built for exactly that case.
Starting with $10,000 and adding $200 a month for 20 years at an assumed 8% average annual return, you would contribute $58,000 out of pocket over that time. With compounding, that grows to a projected portfolio value of about $160,409. Roughly $102,409 of that final total, or about 64%, comes purely from investment growth, not from money you put in directly. In today's dollars, at 2.5% inflation, the same portfolio has the purchasing power of about $97,900.
The two parts of the plan contribute very differently. The $10,000 you start with grows to about $46,600 by itself, while $200 a month grows to about $113,800 by itself. Together they make up the total.
A small change in the assumption makes a large difference over 20 years. For the same $10,000 plus $200 a month:
Because nobody knows what returns will be, planning with a range of rates is wiser than betting on a single number. A conservative rate that you beat is a better surprise than an optimistic one that you miss.
Contributing more is the lever you control. Using the same example:
Increasing contributions when your income rises is one of the easiest ways to improve your outcome without feeling a big change in your budget.
Investment fees, such as fund expense ratios or advisory fees, are subtracted from your return every year. They look small, but they compound just like returns. On the same 8% plan over 20 years:
Enter your fund's annual fee in the calculator and the "lost to fees" row shows what it costs you. Comparing fees before choosing an investment is one of the few things you can control with certainty.
The same plan grows to about $57,600 after 10 years, $160,400 after 20 years, $382,300 after 30 years, and $861,500 after 40 years. Each extra decade multiplies the result far more than it adds in contributions. That is why starting early matters. For a closer look, see the Compound Interest Calculator.
A nominal return is the raw percentage before inflation. A real return subtracts inflation, which shows the growth in purchasing power. The calculator gives you both views: the main figure is nominal, and the "today's dollars" row is the inflation-adjusted equivalent. If you prefer to work in real terms from the start, enter an inflation-adjusted return and set inflation to 0. With a 3% inflation rate, the $160,409 example would be worth about $88,800 in today's dollars.
The math works the same for a 401(k), an IRA, or a taxable brokerage account. For retirement specifically, use the Retirement Calculator, which also handles employer matching, and read how saving 20% of your paycheck connects to your retirement numbers. For a short-term goal with a deadline, the savings goal calculator is a better fit, and the budget calculator can help you find the money to invest.
How accurate is this investment calculator?
It's a planning estimate, not a guarantee. It assumes the same annual return every single year, but real markets fluctuate. Some years will beat your assumed rate, others will lose money. Over long periods the average tends to smooth out, but your actual balance at any given date will differ from a straight-line projection.
What rate of return should I use?
A commonly cited long-run average for a diversified U.S. stock portfolio is around 8-10% per year before inflation, or roughly 6-7% after inflation. A more conservative mixed stock-and-bond portfolio might use a lower assumption, like 5-6%. Try a couple of different rates to see a range of outcomes.
Does this include taxes or investment fees?
Fees, yes: enter the annual fee percentage and the calculator subtracts it from your return. Taxes are not modeled. Taxes on gains and account rules can reduce your actual take-home result, so treat the projection as a pre-tax estimate.
What's the difference between this and a retirement calculator?
The math is the same, but our Retirement Calculator is framed specifically around your current age, target retirement age, and an optional employer 401(k) match. This tool is for any general investment goal with a chosen time horizon, not tied to retirement specifically.
Does this account for inflation?
Yes, as a separate view. The main result is in future dollars, and the "value in today's dollars" row divides it by the cumulative inflation you enter. If you enter a return that is already adjusted for inflation, set inflation to 0 to avoid counting it twice.
Should I invest a lump sum or contribute monthly?
Both work with this calculator. Set the monthly contribution to 0 if you only want to project a one-time investment, or increase it to see how ongoing contributions add to your total. Many investors do both: an initial deposit followed by regular contributions.
What counts as a good annual return?
Historically, broad U.S. stock market indexes have averaged high single digits to low double digits annually over long periods, though any individual year can vary enormously, including significant losses. Bonds and cash historically return less but with lower volatility.
Can I use this for retirement accounts like a 401(k) or IRA?
Yes. The math works the same way regardless of account type. If your employer offers a matching contribution, our Retirement Calculator specifically accounts for that match. This tool assumes all contributions come from you.