US 401(k) Calculator

Traditional pre-tax 401(k) for 2026: employee deferral up to $24,500, plus an $8,000 catch-up at 50+ or $11,250 at ages 60 to 63. The §415 annual-additions limit is $72,000 before catch-up.

Inputs

Compensation

Annual salary

Your annual contribution

Capped at the elective deferral limit.

Your age

yrs

Age 50+ unlocks an $8K catch-up; ages 60 to 63 get an $11,250 catch-up.

Employer match

Employer match %

(decimal)

0.50 = 50¢ per dollar matched.

Match cap (% of salary)

(decimal)

0.06 = match applies up to 6% of salary.

Tax

Marginal federal tax rate

(decimal)

Used to estimate immediate tax savings.

Result

Total going to 401(k) this year

$15,000

Your $12,000 + employer $3,000

Estimated tax savings (this year)

$2,640

At 22% marginal rate

Limits + status

Base elective deferral limit$24,500

Applicable catch-up limit$0

Your employee contribution limit$24,500

§415 annual-additions limit$72,000

Maximum including catch-up$72,000

Compensation considered for match$100,000 of $360,000 max

Employee maxed?No

Combined maxed?No

Age catch-up availableNo (under 50)

Traditional 401(k) only. No Roth 401(k) split, after-tax contributions, or Mega Backdoor mechanics are modeled. Tax savings estimate is federal only at your supplied marginal rate, with no state tax modelled. Uses confirmed 2026 limits.

Same deterministic math runs as a Python package, an MCP server for AI agents, and on this page. No API keys, no network — pure stdlib.

$ pip install calcnook $ uvx calcnook-mcp

>>> from calcnook.countries.us.retirement_accounts import traditional_401k
>>> r = traditional_401k(12_000, 100_000, 0.5, 0.06, 35, 0.22)
>>> r.employer_contribution
3000.0