401(k) Contribution Calculator

A 401(k) is a deferral, a match, and a limit

Payroll withholds a percent of salary. Many U.S. employers add a match on a slice of that deferral. The IRS caps how much you can elect in 2026 ($24,500 under 50, plus catch-up if you qualify). This 401(k) calculator puts those three numbers on one screen and optionally compounds them forward.

It is plan math, not a brokerage login. Enter the match the way your handbook writes it: rate and the salary percent it applies to.

2026 limits this page uses

Elective deferrals (pre-tax and Roth together) stop at $24,500 unless catch-up applies. Standard catch-up is $8,000. Super catch-up for ages 60–63 is $11,250 if the plan offers it. Annual additions (you + employer) are $72,000 before catch-up dollars.

If your percent of salary would exceed the elective cap, the calculator clips the employee line and says so. Excess deferrals are a correction problem, not a flex.

How to use it

Start with the salary on your offer or W-2 box 1-adjacent pay. Enter the percent you actually elect—not the percent you wish you elected. Set match rate and match cap from the SPD. Pick the catch-up band for the age you turn this calendar year.

The projection assumes the same dollar contribution every year, monthly compounding, and a constant return. Raise the years field toward retirement. Then open the paycheck calculator if the next question is what the deferral does to take-home.

Worked examples

On $72,000 with a 6% elective and a 50% match on the first 6%, you put in $4,320 and the employer puts in $2,160 ($6,480 total). That is well under the $24,500 cap. Left at 7% for 25 years with a $25,000 starting balance, this model lands near $581,000.

If you only defer 3% on that same 6% match cap, you leave match on the table. The page will tell you to add about 3 percentage points to collect the full formula.

What this will not do

It will not model after-tax mega backdoor contributions, vesting schedules, loan offsets, or required minimum distributions. A match that vests over four years is not cash until it vests.

For generic compounding without IRS caps, use the compound interest calculator. For the house payment that competes with the deferral, use the mortgage calculator.

Typical examples

Frequently asked questions

What is the 401(k) contribution limit for 2026?

The IRS elective deferral limit is $24,500 if you are under 50. Age 50–59 or 64+ can add an $8,000 catch-up ($32,500 total). Ages 60–63 can use a $11,250 super catch-up if the plan allows ($35,750 total). Combined employee + employer annual additions are $72,000 before catch-up.

How does an employer match work?

A common formula is 50% of what you defer, up to 6% of salary. On $72,000, a 6% deferral is $4,320; a 50% match on that 6% is $2,160. The match does not count against the $24,500 elective limit, but it does count toward the annual-additions cap.

Should I contribute enough to get the full match?

Usually yes—the unmatched percent is free compensation you leave on the table. This page flags how many extra percentage points you need to hit the match cap in the formula you entered.

Does this include the tax break?

Traditional pre-tax deferrals lower taxable wages; Roth 401(k) deferrals do not. Both still count toward the elective limit. Use the paycheck calculator to see take-home after a pre-tax deferral; this page tracks the account, not the stub.

Is 7% a guaranteed return?

No. 7% is a round long-run illustration, not your plan’s menu and not a forecast. Fees, allocation, and sequence of returns will change the ending balance.