US 401(k) Calculator

Traditional pre-tax 401(k) for 2026 — employee deferral up to $24,000 ($32,000 catch-up if 50+), employer match within plan cap, and §415 combined ceiling of $70,000. Tax savings estimated at your marginal bracket.

Inputs

Compensation

Annual salary

Your annual contribution

Capped at the elective deferral limit.

Your age

yrs

50+ unlocks $8K catch-up contribution.

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

Employee elective deferral limit$24,000

Employer + employee §415 limit$70,000

Employee maxed?No

Combined maxed?No

Age catch-up appliedNo (under 50)

Traditional 401(k) only — no Roth 401(k) split, no after-tax contributions, no Mega Backdoor mechanics. Tax savings estimate is for federal only at your supplied marginal rate (no state tax modelled). 2026 limits projected from 2025.

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