401k calculator
A projection, not a promise. Contribution limits, employer match rules and tax treatment change, and investment returns are not a constant 7%. Speak to a financial adviser about your own situation.
A 401k grows from contributions, any employer match and compounding returns. Forty-five thousand at 35, plus 900 a month at 7%, reaches about $1,463,000 by 65 — of which $369,000 is contributions and the rest is growth. At a 4% withdrawal that is roughly $4,877 a month, or about $2,325 a month in today’s money once 2.5% inflation is taken off.
How to project a 401k
The employer match is the part to check first, because it is the only guaranteed return available. A dollar-for-dollar match up to 4% of salary is an instant 100% return on that portion, and no investment will beat it. Anyone contributing below the match threshold is leaving money behind in a way no asset-allocation decision can make up. After that, the two levers are the contribution rate and the number of years, and only one of them can be pulled later.
What waiting five years costs
Run the defaults and the pot reaches $1,463,216.28 at 65. Start the same contributions at 40 instead of 35 and it reaches $986,708. The delay costs $476,508, and the contributions skipped in those five years total $54,000. Nine dollars of final balance for every dollar not paid in. The reason is not that early dollars are special; it is that they are the dollars with thirty years of compounding left, and by the last decade the growth on the existing balance is doing far more work than anything new arriving. On these settings, $1,094,216.28 of the final pot is growth and $369,000 is money paid in, so three quarters of the answer was never contributed by anyone.
The two contribution limits are different numbers
The monthly field here is meant to hold everything going into the account, your own deferrals and the employer match together, and it enforces no ceiling. Two ceilings exist. Your own elective deferrals cap at $24,500 for 2026, rising by an $8,000 catch-up from age 50 and by $11,250 between 60 and 63. Everything going into the account from all sources caps at $72,000, or $80,000 including catch-up and up to $83,250 for the 60 to 63 band. A figure typed above that passes the first test can still fail the second, and this page will project it anyway.
The withdrawal row is nominal, and that matters more than it looks
A 4% withdrawal on $1,463,216.28 is $58,528.65 a year, or $4,877.39 a month. In today’s prices, after thirty years at 2.5% inflation, that is $2,325.26 a month. Both figures are true and they describe the same money. Plan against the second one.
What people use it for
- Checking whether you are on track for retirement
- Seeing what raising your contribution rate does
- Comparing retiring at 62 against 67
- Estimating the income a pot will support
- Putting a number on the cost of delaying by a few years
- Sanity-checking a total contribution against the annual limits
Questions
On the defaults, $1,463,216.28 at 65: $369,000 contributed and $1,094,216.28 of growth. The year-by-year table shows how the split gets there.
Just under three quarters, 74.8%. The proportion rises with every extra year, because growth compounds and contributions do not.
Enormously. Beginning at 40 rather than 35 ends at $986,708 instead of $1,463,216.28. The $54,000 of skipped contributions cost $476,508 of final balance.
More than to anything else. Six per cent gives $1,175,079 and eight per cent gives $1,833,431 against the default $1,463,216.28, so two percentage points move the answer by two thirds of a million.
Yes, in the monthly contribution. It is real money going into the account and it compounds like the rest.
Two of them, and this page enforces neither. Your own deferrals cap at $24,500 for 2026; everything from all sources together caps at $72,000.
A catch-up of $8,000 applies for 2026, and $11,250 instead between the ages of 60 and 63. The combined ceiling rises to $80,000, or $83,250 in that band.
It takes the default pot to $1,707,210, up $243,994 on $72,000 more paid in over thirty years.
A rule of thumb that withdrawing 4% of the pot in the first year, then adjusting for inflation, has historically lasted 30 years. It is a starting point, not a guarantee, and the historical record it rests on is a single country over a single century.
The monthly income in today’s money falls from $2,325.26 to $1,743.94. The pot is unchanged; only the rate you draw from it moves.
The real one, for planning. $4,877.39 a month in thirty years is $2,325.26 at today’s prices, and the second figure is the one that buys groceries.
$2,138,726 instead of $1,463,216.28, and $3,004 a month in today’s money instead of $2,325. Five extra years of contributions and five fewer years of drawing down both push the same way.
$1,157,636 and $1,981 a month in today’s money. Three years short of the default costs about a fifth of the pot.
No. A traditional 401(k) is taxed on withdrawal and a Roth is not, so the same projected pot supports different spendable incomes depending on which one it sits in.
No. It grows the balance at a constant rate every month, which no market does. Use it to compare two decisions under identical assumptions, not to predict a balance.