How much will my investment be worth?

Before tax, $25,000 plus $600 a month at 7% becomes a large figure over 25 years, but the number that matters is what it buys. After tax and 3% inflation, the real value is a good deal lower, and the calculator shows all three balances side by side rather than only the flattering one.

Does a taxable account or a Roth end up with more?

A Roth, and by more than the headline tax rate suggests. A taxable account is taxed on gains as they arise, so the drag compounds every year; a Roth compounds untouched. Switch the account type above and compare, the gap widens the longer the horizon, because it is a difference in compounding rather than a one-off deduction.

Is 7% a realistic return to assume?

It is a common long-run average for a diversified equity portfolio before inflation, and a poor description of any single decade. It is also before fees. If you want a figure in today’s money directly, enter your expected return minus expected inflation, around 4%, and set inflation to zero.

Why is the real value so much lower than the balance?

Because inflation erodes purchasing power for the whole period the money is invested. At 3%, money loses roughly half its value in 23 years, so a balance projected decades out buys far less than the number implies. The inflation calculator shows that effect on its own.

How much difference do fund fees make?

More than most people expect, because they compound like a negative return. A 1% annual expense ratio over thirty years costs roughly a quarter of the final balance, comparable to the entire tax effect modelled here, and considerably easier to avoid. Fees are not included in these figures, so subtract yours from the expected return to account for them.

Should I invest this money or pay off debt with it?

Compare the return against the debt’s rate after tax. Paying down a debt is a guaranteed return equal to its interest rate, which an uncertain market return has to beat. Mortgage payoff versus investing and car loan payoff versus investing both solve for the exact bar.

Investment Calculator

This investment calculator gives the balance before tax, after tax and in today’s money, because only the last of those is comparable to prices you know. The gross figure is the easy one and the least useful; tax and inflation usually take a bigger share of it than people expect.

Example numbers

The answerfrom an example

This grows to $480,485 before tax, but $229,483 once tax and inflation are taken, which is what it will actually buy.

Worked on $25,000 to start, $600 a month at 7% for 25 years. Change anything below to use yours.

Balance before tax: $480,485
After tax: $480,485
In today’s money: $229,483

The figures behind it

Balance before tax: $480,485; After 25 years, in the dollars of that year.
After tax: $480,485; A taxable account is taxed on gains as they are earned, so the drag is already in the balance above.
In today’s money: $229,483; After tax and after 3.0% inflation. This is the figure that means something.
You will have paid in: $205,000; Starting balance plus every contribution.
Growth did the rest: $275,485; 57.3% of the balance is money you never contributed.
Lost to tax and inflation: $399,696; $148,693 to tax and $251,003 to inflation, against an untaxed nominal balance.

What the balance is really made of$480,485

37%

57%

Starting balance$25,000
Contributions$180,000
Investment growthMoney the money made.$275,485

The balance against what you put in

Years from today

BalanceWhat you put in

Payment scheduleShow

The table scrolls sideways

Year	Monthly in	Paid in to date	Growth to date	Balance
1	$600	$32,200	$1,583	$33,783
2	$600	$39,400	$3,657	$43,057
3	$600	$46,600	$6,251	$52,851
4	$600	$53,800	$9,392	$63,192
5	$600	$61,000	$13,113	$74,113
6	$600	$68,200	$17,446	$85,646
7	$600	$75,400	$22,424	$97,824
8	$600	$82,600	$28,084	$110,684
9	$600	$89,800	$34,463	$124,263
10	$600	$97,000	$41,603	$138,603
11	$600	$104,200	$49,546	$153,746
12	$600	$111,400	$58,337	$169,737
13	$600	$118,600	$68,023	$186,623
14	$600	$125,800	$78,655	$204,455
15	$600	$133,000	$90,285	$223,285
16	$600	$140,200	$102,969	$243,169
17	$600	$147,400	$116,766	$264,166
18	$600	$154,600	$131,739	$286,339
19	$600	$161,800	$147,953	$309,753
20	$600	$169,000	$165,478	$334,478
21	$600	$176,200	$184,388	$360,588
22	$600	$183,400	$204,759	$388,159
23	$600	$190,600	$226,674	$417,274
24	$600	$197,800	$250,219	$448,019
25	$600	$205,000	$275,485	$480,485

What this result assumes

The return is held constant. No market delivers the same figure every year, and a smooth curve says nothing about the range of outcomes around it, which near the end of a long horizon is the risk that matters most.
A taxable account is modelled as paying tax on gains each year at your marginal rate, applied as a drag on the return. That is harsher than reality, where qualified dividends and long-term gains are taxed more lightly and only when realised, so this errs against the taxable case.
The real figure divides the after-tax balance by cumulative inflation. It is the only number here directly comparable to prices you know today.
Fund expense ratios, advisory fees and trading costs are excluded. They compound against you exactly as returns compound for you, 1% a year over thirty years is roughly a quarter of the final balance.

Methodology

Reviewed September 1, 2026

Three balances, and which one matters

A projection that reports one number reports the wrong one. The gross balance is what the market delivered; it is the figure every calculator shows and the least useful of the three. Two things stand between it and what the money will do for you.

Tax comes first, and it depends entirely on the wrapper. A Roth is never taxed again. A traditional 401(k) or IRA compounds untouched and is then taxed in full at withdrawal. A taxable account is different in kind — it is taxed on gains as they arise, so the drag compounds year after year rather than landing once at the end. That is why a taxable account ends below a Roth even before any withdrawal tax is considered.

Inflation comes second, and it applies to all three. Dividing the after-tax balance by cumulative inflation restates it in today’s money, which is the only version directly comparable to prices you actually know. On the default figures, the gap between the headline number and that one is large enough to change what you would decide.

How the tax is applied

The taxable case multiplies the return itself by one minus your marginal rate, so the tax compounds against you exactly as growth compounds for you. This is deliberately harsher than reality: qualified dividends and long-term capital gains are taxed more lightly than ordinary income, and only when realised rather than annually. The simplification errs against the taxable account rather than for it, which is the safer direction.

The tax-deferred case leaves the balance alone and applies your marginal rate to the whole of it at the horizon. The deduction you received on the way in is not modelled, which makes that figure conservative too — the real advantage of a traditional account is larger than shown.

The tax figure reported in the stats compares against an untaxed nominal balance, so it is meaningful across all three account types rather than only counting a terminal charge that two of them never pay.

What a constant return hides

Every figure here assumes the return arrives smoothly. It does not. A 7% average made of +25%, −18% and +14% is not the same investment as 7% three times, and the difference is largest exactly when the balance is largest — in the years just before you need the money.

This model cannot show that. It compares expected values, and a single line drawn through them should be read as an illustration of a mechanism rather than a forecast of an outcome. If the money is needed on a date, the savings goal calculator with a deposit rate is a more honest tool than this one with an equity return.

Fees are the other omission, and they behave like a negative return. An expense ratio of 1% a year over thirty years costs roughly a quarter of the final balance — comparable to the entire effect of the tax modelled above, and rather easier to avoid.

Assumptions

The return is constant every year, with no volatility and no sequence-of-returns risk.
Contributions are made at the end of each month and never missed.
Any annual step-up applies on the anniversary rather than gradually.
A taxable account is taxed annually on gains at your marginal rate, harsher than real capital-gains treatment.
A tax-deferred balance is taxed in full at withdrawal; the up-front deduction is not modelled.
The marginal rate is the same when contributing and when withdrawing.
Inflation is a constant annual rate applied to restate the final balance only.
Fund expense ratios, advisory fees and trading costs are excluded.
Contribution limits, employer matches and withdrawal rules are not modelled.

Sources

Common questions

How much will my investment be worth?: Before tax, $25,000 plus $600 a month at 7% becomes a large figure over 25 years, but the number that matters is what it buys. After tax and 3% inflation, the real value is a good deal lower, and the calculator shows all three balances side by side rather than only the flattering one.
Does a taxable account or a Roth end up with more?: A Roth, and by more than the headline tax rate suggests. A taxable account is taxed on gains as they arise, so the drag compounds every year; a Roth compounds untouched. Switch the account type above and compare, the gap widens the longer the horizon, because it is a difference in compounding rather than a one-off deduction.
Is 7% a realistic return to assume?: It is a common long-run average for a diversified equity portfolio before inflation, and a poor description of any single decade. It is also before fees. If you want a figure in today’s money directly, enter your expected return minus expected inflation, around 4%, and set inflation to zero.
Why is the real value so much lower than the balance?: Because inflation erodes purchasing power for the whole period the money is invested. At 3%, money loses roughly half its value in 23 years, so a balance projected decades out buys far less than the number implies. The inflation calculator shows that effect on its own.
How much difference do fund fees make?: More than most people expect, because they compound like a negative return. A 1% annual expense ratio over thirty years costs roughly a quarter of the final balance, comparable to the entire tax effect modelled here, and considerably easier to avoid. Fees are not included in these figures, so subtract yours from the expected return to account for them.
Should I invest this money or pay off debt with it?: Compare the return against the debt’s rate after tax. Paying down a debt is a guaranteed return equal to its interest rate, which an uncertain market return has to beat. Mortgage payoff versus investing and car loan payoff versus investing both solve for the exact bar.

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