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ETF & Index Fund Calculator · Growth, Fees and Inflation

An index fund or ETF lets you own a slice of an entire market, such as the 500 largest US companies, for a very small yearly fee. Investing a fixed amount every month, often called dollar-cost averaging, is the simplest way to use one: you buy more shares when prices are low and fewer when they are high, and the money compounds because the returns you earn are reinvested and start earning returns of their own. This calculator shows what that habit can add up to.
Enter what you can start with, how much you will add each month, how many years you will invest and the yearly return you expect. The calculator grows the balance month by month and reports the final balance, how much of it is money you paid in and how much is investment growth. It can also raise your contributions by a set percentage each year, to reflect pay raises, and it lets you choose whether the monthly deposit happens at the start or the end of the month.
Two features separate it from a basic compound interest calculator. First, the fund expense ratio: every fund charges a yearly fee that is taken out of its return, and over decades a small difference becomes large. The calculator shows how much you lose to the fee compared with a fund that charged nothing, so you can see what a 0.03% index ETF saves you over a 0.75% managed fund. Second, inflation: a balance of several hundred thousand dollars in 30 years will buy less than it does today, so the result is also shown in today's dollars. Returns are an assumption you choose, not a forecast. Broad US stock funds have averaged roughly 10% a year before inflation over the long run but with big swings, and taxes on dividends and gains are not deducted.
Standard: 10000
Standard: 500
Standard: 30
Broad US stock funds have averaged roughly 10% a year before inflation over the long run, but returns vary and are not guaranteed
The yearly fee of the fund. Many broad index ETFs charge 0.03%–0.10%; actively managed funds often charge 0.5%–1%
Optional: raise your monthly amount by this much every year
Used to show the result in today's dollars
Expected Return:
Years:
Fund Expense Ratio:

Detailed Breakdown

8 metrics
PRIMARY RESULT
$654,429.39
Estimated Balance After 30 Years
Total You Contribute
$190,000.00
Investment Growth
$464,429.39
Share of the Balance That Is Growth
70.97%
Value in Today's Dollars
$311,994.42
Return After Fund Fees
6.95%
Lost to Fund Fees
$6,419.46
Balance With No Fund Fees
$660,848.85

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exploreReal-World Scenarios

When to Use This Calculator

Everyday financial situations where this tool gives you fast, accurate clarity:

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Project Your Portfolio

See what monthly investing in an index fund can grow to over 10, 20 or 40 years.

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See What Fund Fees Cost

Compare a 0.03% index ETF with a 0.75% managed fund and see the dollars lost to the fee.

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Look at the Real Value

Convert the future balance to today's dollars to judge what it will really buy.

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Plan Rising Contributions

Add a yearly increase to model raising your monthly investment as your income grows.

Calculation Formula

Standard Method

Net Yearly Return = Expected Return − Fund Expense Ratio Monthly Rate = (1 + Net Yearly Return)^(1/12) − 1 Each Month: Balance = Balance × (1 + Monthly Rate), plus the monthly contribution (at the end or the start of the month) Contributions can rise by a fixed percentage every 12 months Total You Contribute = Starting Amount + All Monthly Contributions Investment Growth = Final Balance − Total You Contribute Value in Today's Dollars = Final Balance ÷ (1 + Inflation)^Years Lost to Fund Fees = Balance With a 0% Expense Ratio − Balance With Your Expense Ratio For level contributions at the end of each month the balance equals Starting Amount × (1 + Net Return)^Years + Contribution × ((1 + i)^n − 1) ÷ i, with i the monthly rate and n the number of months. The calculator does not deduct taxes on dividends or gains, brokerage costs or the bid-ask spread.

Benchmark Example:
$10,000 to start, $500 a month for 30 years, an expected return of 7% and a fund with a 0.05% expense ratio: • Return after fund fees: 7% − 0.05% = 6.95% a year • Estimated balance after 30 years: $654,429.39 • You contribute: $10,000 + $500 × 360 = $190,000 • Investment growth: $464,429.39, which is 71% of the final balance • With 2.5% inflation, the balance is worth $311,994.42 in today's dollars • Lost to the fund fee: $6,419.46 compared with a fund that charged nothing If the same money were in a managed fund with a 0.75% expense ratio, the balance would be $571,438.10, which is $89,410.75 less than a fee-free fund, about $83,000 less than the 0.05% index fund.

Frequently Asked Questions

6 answers

Applicable Laws & Regulatory Standards

Securities and Exchange Commission & Internal Revenue Service

Official Legal Reference
Investment Company Act of 1940 — 15 U.S.C. § 80a-1 et seq.

Regulates mutual funds and exchange-traded funds registered in the United States, including how they are organized, how they hold investors' assets and what they must disclose.

SEC Form N-1A (17 CFR 239.15A and 274.11A) — fund prospectus fee table

Requires a fund to show its fees and expenses in a standard table at the front of the prospectus, including the expense ratio, so funds can be compared before investing.

Internal Revenue Code § 1(h) (Maximum Capital Gains Rate)

Sets the lower tax rates for long-term capital gains and qualified dividends that apply to profits on ETFs and index funds held for more than a year, which this calculator does not deduct.

Legal citations and statutes are provided for consumer transparency, analytical validation, and educational reference under U.S. consumer financial regulations. This tool is not a substitute for formal legal, accounting, or tax counsel.

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