401(k) Calculator

A 401(k) balance is never one number. It is four numbers stacked on top of each other: what was already in the account, what you defer out of every payday, what your employer adds on top, and what the market turns all three into over the years you leave it alone. This 401(k) calculator runs that stack forward year by year and draws the result as proportional bars rather than a single total, because the shape of the split is the part that changes how people behave.

Drag the contribution slider and three things move at once. Your own bar grows, which is obvious. The employer bar grows too, but only until you cross the match cap, at which point it stops dead no matter how far you keep dragging. And the growth bar swells faster than either, because every extra dollar in the account spends the rest of the projection earning. Those three behaviours are the whole subject, and they are easier to see than to read about.

The three sources of money

Your own deferrals are the only part you fully control, and they are the only part that is always yours from the first day. The Internal Revenue Service is explicit that an employee's elective deferrals are 100 percent vested immediately. Employer money is different. A plan may hold it behind a cliff schedule that hands it over in one piece after three years of service, or a graded schedule that releases it in slices over six. Leave early and the unvested slice goes back to the plan, which is the single reason a projection like this one can overstate what you would walk away with.

Investment growth is the part nobody contributes. It arrives because the account is tax deferred, so nothing is skimmed off dividends or realised gains along the way and the entire balance keeps compounding on itself. Over a short projection that hardly matters. Over thirty years it becomes the majority of the balance, and the bars above make that obvious in a way a total never does.

What the employer match is actually worth

Matched pay is the only money in personal finance that returns something before the market has done anything at all. A 50 percent match is an instant 50 percent on the matched slice, in the year it is paid, regardless of what markets do afterwards. A dollar for dollar match doubles it. Nothing else available to an ordinary saver behaves like that, which is why the calculator prints a warning in dollars rather than in adjectives when you are deferring below the cap.

Match formulas vary more than people expect. Fidelity reports that the most common formula across the plans it administers is a dollar for dollar match on the first 3 percent of pay and then 50 cents on the dollar on the next 2 percent, which is worth 4 percent of salary to someone deferring 5. Across all ages the average employer contribution on those plans was 4.8 percent of pay in the first quarter of 2026, and more than 85 percent of the plans offered some employer contribution at all. This page models a single tier, which covers the majority of plans; if yours is tiered, enter the cap as the point where the money stops and the rate as the blended figure your plan document implies.

The 2026 limits, and which ones bite

Three separate ceilings apply, and most calculators apply none of them. The first is the elective deferral limit, which for 2026 is $24,500. It governs your side only, so the employer match does not count against it. From the year you turn 50 a catch-up of $8,000 is added on top, taking you to $32,500. For the four years in which you are 60, 61, 62 or 63 a larger catch-up of $11,250 is taken instead of the $8,000, not in addition to it, which lifts the ceiling to $35,750 and then drops it back at 64. The calculator applies the right band to every single year of the projection, which is why a long run through your fifties and sixties shows the deferral figure stepping up twice and back down once.

The second ceiling is the annual additions limit, $72,000 for 2026. It covers everything credited to your account in a year: your deferrals, the match, any profit sharing contribution and any reallocated forfeitures. Catch-up money sits outside it, so the effective total is $80,000 from age 50 and $83,250 in the 60 to 63 band. Someone with a generous match and a high deferral rate can hit this, and when they do it is the employer money that gets trimmed, because your own deferrals were already capped.

The third is the compensation limit of $360,000. No plan may count pay above it for any purpose. A saver on $500,000 with a 6 percent match cap receives the match on $360,000, not on $500,000, and every calculator that ignores this overstates high earner projections. All three limits come from IRS Notice 2025-67 and all three are indexed, so they move most years. The reference table above carries the date they were checked.

The assumptions you are making

Every slider above the return field is a fact about your life. The return slider is not. It is a guess, and a thirty year projection is exquisitely sensitive to it. Competitor calculators default to 6 or 7 percent; this page defaults to 7 and says plainly that it is an assumption rather than a forecast. Move it to 5 and to 9 and look at the gap between the two answers. That gap is the honest width of the estimate, and it is usually wider than the difference any contribution decision makes.

The pay rise slider compounds in the same quiet way. A 2.5 percent annual rise turns a $75,000 salary into roughly $155,000 over thirty years, and since your deferral is a percentage, every rise lifts both your bar and the employer bar without you touching anything. Setting it to zero is the conservative choice and produces a deliberately pessimistic projection.

What this projection leaves out

Fees are not modelled. A plan charging 0.75 percent a year is effectively reducing the return slider by 0.75, so subtract yours before you drag it. Tax is not modelled either: a traditional 401(k) balance is pre-tax money, so the figure above is not what you get to spend, while a Roth 401(k) balance is already taxed and broadly is. Vesting is not modelled, for the reason given earlier. Nor is the withdrawal end of the account, where a distribution before age 59 and a half generally carries a 10 percent additional tax unless an exception applies, the best known being separation from service at or after 55, and where required minimum distributions begin at 73 unless you are still working for the plan sponsor and own less than 5 percent of it.

1. 1Claim the whole match first

   Set the contribution slider to at least the match cap before anything else. On $75,000 with a 50 percent match to 6 percent, moving from 3 percent to 6 percent costs you $2,250 of deferred pay and collects $1,125 of employer money in year one, every year, before growth.

2. 2Then test the return, not the contribution

   Drag the return slider between 5 and 9 percent and watch the total swing. If the swing dwarfs the effect of a two point contribution change, your plan is sound and the uncertainty is the market, not your saving rate.

3. 3Watch for the limit notices

   If a badge appears under the bars, a ceiling is binding somewhere in the projection. The year by year table marks which years, so you can see whether it is one late year or a decade of them.

4. 4Compare the shape, not just the total

   Run the same salary starting at 25 and at 40. The totals differ, but the telling difference is the growth bar, which carries most of the balance in the first case and a minority of it in the second. That is the argument for starting early, drawn rather than asserted.

When you want the same compounding without the plan rules attached, the compound interest calculator strips it back to one balance and one rate, and the investment calculator handles regular contributions into an ordinary account with no match and no ceiling.