Project how a 401(k) grows from salary, your contribution rate, the employer match, and investment return; see what an early withdrawal actually nets after tax and the 10% penalty; or find the contribution percentage window that captures the full match without hitting the IRS cap mid-year.
2026 contribution limits
| Age | Employee deferral cap |
|---|---|
| Under 50 | $24,500 |
| 50 or older | $32,500 |
| 60–63 (SECURE 2.0 enhanced catch-up) | $35,750 |
The overall employee-plus-employer addition limit is $72,000 in 2026 (not modeled here — elective deferrals bind first for typical match formulas).
Examples
Default projection (age 30, retire at 65)
A 30-year-old earning $75,000, with $35,000 already saved, contributing 10% and receiving a 50% match on the first 3%, at a 6% return and 3% inflation / salary growth, reaches about $1,711,800 at 65 — $608,345 in today's purchasing power. A fixed purchasing-power withdrawal is $9,494 a month from age 66 ( $3,374 today).
Early withdrawal of $10,000
At 25% federal and 5% state tax, still employed, a $10,000 early withdrawal keeps $6,000. The 10% penalty is $1,000, federal tax $2,500, and state tax $500. A qualifying disability or the rule of 55 drops the penalty and you keep $7,000.
Maximize a two-tier match
On $75,000 with 50% of the first 3% plus 20% up to 6%, contribute between 6% and 32.67% of pay. 6% puts $4,500 of yours and $1,575 of match in the plan; 32.67% is the $24,500 IRS cap, still with $1,575 of match.
Formula
Each working year uses this projection loop:
salary_t = income × (1 + salary increase)^(t − 1)
employee_t = min(salary_t × contribution %, IRS deferral cap)
match_t = (salary paid while contributing) × match % × min(contribution %, match limit)
C_t = employee_t + match_t
return_t = prior balance × r + C_t × r / 2
end_t = prior balance + C_t + return_t
The IRS cap starts at $24,500 (2026) and grows with your inflation rate; at ages 50–59 and 64+ it adds the flat $8,000 catch-up; ages 60–63 use the $11,250 enhanced catch-up. If contributions would exceed the cap, they stop mid-year and so does the match.
In retirement, three withdrawal options are sized so the balance reaches $0 at life expectancy:
fixed PP monthly = PMT(inflation / 12, years in retirement × 12, nest egg)
fixed monthly = PMT(return / 12, years in retirement × 12, nest egg)
fixed annual = PMT(return, years in retirement, nest egg)
Today's dollars divide by (1 + inflation)^years to retirement (or to age 85 for the last-year figures).
Check your plan document for its match formula, vesting schedule, eligible compensation, and any year-end true-up. Those details determine whether reaching the annual limit early affects the match.
Sources and limits
The contribution caps come from the IRS 401(k) contribution-limit guidance. Early-distribution exceptions vary by circumstance; review the IRS early-distribution guidance. The calculator does not model vesting, nondiscrimination limits, Roth versus pretax tax treatment, fees, loans, required minimum distributions, or an individual plan's true-up rules.