401(k) Contribution Calculator
Legal basis: IRC §402(g) (elective deferral limit); IRC §414(v) (catch-up contributions); IRC §415(c) (annual additions limit) · checked 2026-10-04 · Rates and limits change — verify the current figures.
The 401(k) is the workhorse of US retirement saving, and its limits come from three different code sections that move almost every year. IRC Section 402(g) caps your elective deferrals - the money you divert from your paycheck before tax into the plan. Section 414(v) adds a catch-up for workers 50 and older, and since 2025 the SECURE 2.0 Act adds a higher catch-up for workers aged 60 through 63. Section 415(c) separately caps the total annual additions to your account from every source: your deferrals, catch-ups, employer match, and profit sharing combined.
The deferral limit applies to you as a person, not to a plan. If you work two jobs with 401(k)s, your combined elective deferrals cannot exceed the Section 402(g) limit, even though each employer's match counts separately against its own Section 415(c) cap. Catch-up deferrals only exist for workers 50 and older; the enhanced amount for ages 60-63 replaces, rather than adds to, the standard catch-up. All of these dollar figures are indexed and change annually, so this calculator makes them inputs - check the current year's numbers before relying on any default.
The employer match is the highest-return part of the decision. A typical formula matches 50 percent of the first 6 percent of pay: defer less than 6 percent and you leave immediate, guaranteed money unclaimed. The match is limited to the matched portion of your deferral, is added on top of your own contribution, and does not reduce your personal deferral room, though it does count toward the total additions cap. Matches are increasingly paid as Roth matches under SECURE 2.0, which changes their tax treatment but not the arithmetic here.
Enter your salary, age, intended deferral percentage, and the current-year limits. The calculator shows your elective deferrals, the catch-up tier you fall into, the employer match under a common formula, the combined total against the annual additions cap, and how much match you would forfeit by deferring less than the match threshold.
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How the math works
- Elective deferral = min(salary × deferral %, §402(g) limit), plus the catch-up amount for your age tier (50+ standard, 60-63 enhanced).
- Employer match = salary × min(deferral %, match threshold %) × match rate. A 50% match on the first 6% of pay means deferring at least 6% captures the full match.
- Total annual additions = your deferrals + catch-up + employer match + profit sharing, capped by the §415(c) limit.
- All dollar limits are indexed annually; enter the current-year figures from the IRS cost-of-living notice.
Frequently asked questions
How much can I defer into my 401(k)?
How does the catch-up contribution work?
Does the employer match count against my deferral limit?
How do I capture the full employer match?
What is the total annual additions limit?
What happens if I overdefer?
Should I defer before tax or as Roth?
This calculator is an educational estimate, not tax or financial advice. Deferral limits, catch-up amounts, and the annual additions cap change every year, and match formulas vary by plan. Verify the current-year figures with the IRS or your plan documents and confirm decisions with a CPA or fiduciary adviser.