Investment Calculator

The short answer

• $10,000 plus $500 a month for 30 years at 7% a year, with 0.5% fees, grows to about $595,755.
• You put in $190,000; growth adds $405,755.
• The 0.5% fee costs about $65,093 by year 30, counting the growth the fees would have earned.
• At 2.5% inflation, the final balance buys about what $284,022 buys today.

How the calculator works

The calculator works month by month. Each month your balance grows at a twelfth of the yearly return (compounded), the fund’s fee is taken as a twelfth of the yearly expense ratio, and your monthly investment is added at the end of the month. Once a year your monthly amount rises if you asked it to.

In a taxable account, the dividend part of the return is taxed each December and the tax comes out of the account, and when you sell at the end, tax is due on the gain over what you paid (your cost basis, which includes reinvested dividends). The "with no fees" line runs the same plan without the fee, so the gap between the two lines is the full cost of fees.

A worked example

The fees you pay directly add up to $32,477, but the true cost is about twice that, $65,093, because every dollar taken in fees would otherwise have compounded until year 30.

How the balance builds

Growth is slow at first and fast later. In the first ten years the balance gains $31,918 on top of contributions; in the last five years alone it gains $155,922. The cost of fees grows the same way: it is tiny early on and large by the end.

What return to expect

No calculator knows future returns. Over very long periods, broad US stock indexes have averaged roughly 10% a year before inflation, and high-quality bonds much less, but those averages include decades well above and well below them. Because a plan that only works in good markets is fragile, many planners use 5% to 7% a year for a portfolio of mostly stocks with some bonds, and lower figures for more conservative mixes.

Planning with several returns

Your contributions are the same $190,000 each time, yet the results range from $341,591 to $1,078,042. In today’s dollars that is about $162,851 to $513,949. The calculator shows these scenarios for your own figures, so you can check a plan still works if returns disappoint.

How fees eat into growth

A 1% fee sounds small, but it is charged on everything you have invested, every year. Here it costs $122,892 over 30 years, nearly two-thirds of what you put in. Moving from a 1% fund to a 0.05% index fund would add $116,027 to the final balance with no extra saving and no extra risk.

Typical fees in 2025

Fees have fallen steadily for decades as investors moved to index funds and cheaper share classes. Many broad index funds and ETFs now charge 0.10% or less. A fund’s expense ratio is listed on the first pages of its prospectus and on any fund research site.

A lump sum and fees

$100,000 invested once at 7% for 20 years grows to about $350,136 with a 0.5% fee, but only $286,619 with a 1.5% fee. The difference, $63,517, is money you would never see on a statement: it simply isn’t there.

Time in the market

Going from 30 to 40 years adds $60,000 of contributions but about $602,225 of balance: the balance roughly doubles. Starting early is the most powerful lever you have. The compound interest calculator shows the same effect for a single rate.

Raising your contributions

Under More options you can raise your monthly amount each year. Raising $500 a month by 3% a year lifts the 30-year example from $595,755 to about $800,377, for $295,452 of contributions. Linking increases to pay raises means your take-home pay still rises, just a little less. Many 401(k) plans offer automatic yearly increases.

Real returns after inflation

A balance decades from now buys less than the same number of dollars today. At 2.5% inflation, prices roughly double in 28 years, so the $595,755 in the example is worth about $284,022in today’s money. Use the today’s-dollars figure when you compare the result with a goal such as retirement spending. Our inflation calculator shows how prices have changed since 1913.

Taxable vs tax-advantaged accounts

Same example, with a 1.5% dividend yield taxed at 15% each year and gains taxed at 15% on selling. The taxable account ends about $70,980 behind a Roth IRA, where qualified withdrawals are tax-free. In a traditional 401(k) or IRA, withdrawals are taxed as income instead, so the comparison depends on your tax rate in retirement. The Roth IRA calculator covers that choice.

How investment income is taxed

• Qualified dividends and long-term gains (investments held more than a year): 0%, 15% or 20% federally in 2026, depending on taxable income.
• Short-term gains and interest: taxed as ordinary income at your bracket rate.
• Net investment income tax: an extra 3.8% above $200,000 of modified AGI for single filers ($250,000 married filing jointly).
• State tax: most states tax investment income as ordinary income.

The capital gains tax calculator works out the rate that applies to your own gains.

Lump sum or monthly investing

If you have a lump sum, investing it all at once has usually beaten spreading it over months, because markets rise more often than they fall. Investing gradually, called dollar-cost averaging, buys more shares when prices are low and fewer when they are high, and protects you from investing everything just before a fall. For most people the question doesn’t arise: they invest a fixed amount from each paycheck, which is dollar-cost averaging by default.

Stocks, bonds and risk

Stocks have offered the highest long-run returns but the biggest swings. Bonds pay less but fall less. Cash is stable but often barely keeps up with inflation. Your mix, called asset allocation, should fit how long you will invest and how much of a fall you could live with without selling. A common approach is to hold more stocks when the goal is decades away and shift toward bonds as it nears.

Averages hide the swings

The calculator uses the same return every year. Real returns arrive unevenly: a portfolio might gain 20% one year and lose 15% the next. With regular contributions, early falls can even help, because your monthly amount buys more shares. Falls close to the date you need the money hurt most, which is why people reduce risk as a goal approaches.

Which account to fill first

1. Your 401(k) up to the full employer match.
2. A health savings account if you have a high-deductible health plan.
3. A Roth or traditional IRA.
4. More 401(k), up to the $24,500 limit for 2026.
5. A taxable brokerage account for anything beyond, or for goals before retirement.

Common mistakes

• Ignoring fees because they look small as a percentage.
• Planning on a single optimistic return.
• Comparing a future balance with today’s prices without adjusting for inflation.
• Investing in a taxable account while leaving an employer match unclaimed.
• Selling in a panic after a market fall.

Using the calculator well

• Check your funds’ expense ratios and enter the weighted average.
• Look at the scenarios table: make sure the lower returns still meet your goal.
• Use the today’s-dollars figure when comparing with spending goals.
• Copy the link to save your figures and come back each year.

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