401K Calculator
Adjust the inputs below. Results update as you type.
How it works
A 401(k) projection estimates how employee deferrals, employer match, and assumed returns could grow inside a workplace retirement plan. Traditional contributions typically reduce taxable wages today; Roth 401(k) contributions (when offered) are after-tax with different withdrawal tax treatment. This calculator models growth for planning education, not contribution-limit legal advice.
Enter current balance, contribution rate or dollar amount, salary, match formula if known, expected return, and years until withdrawal. Employer match is part of compensation—missing the match is often an immediate return left on the table. Contribution limits and catch-up rules change; verify the current plan year limits with your plan notice or IRS guidance.
Compare traditional vs Roth using tax assumptions for today versus retirement, and pair results with a paycheck estimate so higher deferrals still leave enough take-home pay. Fees and fund choices affect real outcomes more than many people expect; a slightly lower fee can matter as much as a slightly higher assumed return over decades.
Input guidance
- Salary and deferral percent should match your plan’s eligible compensation definition when possible.
- Enter the employer match formula accurately—missing match is costly.
- Choose traditional vs Roth framing based on tax timing, not only headline growth.
The formula
Each year, contributions (your % of salary plus the employer match) are added and the whole balance grows by the expected return: balance = (balance + annual contributions) × (1 + return), repeated yearly.
Worked example
On an $80,000 salary, contributing 10% ($8,000) with a 50% match up to 6% ($2,400) adds $10,400/year. At 7% for 30 years that grows to roughly $980,000.
More examples to test
- 6% deferral with 50% match on 6%: compare employee + employer annual additions.
- Same contribution as Roth vs traditional: note that paycheck impact differs even if growth assumptions match.
How to interpret results
Growth results show plan mathematics under steady returns. Confirm limits, vesting, and fees with your plan documents.
When this can be inaccurate
Contribution limits, after-tax mega backdoor rules, and loan provisions are not fully modeled.
Change history
- July 2026: Traditional/Roth framing and match capture notes expanded.
- June 2026: Contribution growth model reviewed.
Site-wide corrections also appear on the corrections log.
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Frequently asked questions
Should I always get the full employer match?+
Yes, if you can. The match is an instant, guaranteed return on your contribution — leaving it on the table means turning down free retirement money.
What is the contribution limit?+
The IRS sets an annual employee contribution cap that rises most years, with an extra catch-up amount allowed once you are 50 or older.
Traditional or Roth 401(k)?+
Traditional lowers taxable income now and is taxed at withdrawal; Roth is funded with after-tax money and grows tax-free. The better choice depends on your current vs. future tax rate.
How should I use this result?+
Treat it as a planning estimate. Compare at least two realistic scenarios, then confirm with statements, quotes, or a qualified professional before acting.
How often should I refresh assumptions?+
Refresh whenever rates, income, costs, or policy limits change materially, and before making irreversible commitments.
Guided next steps
Want the full workflow? Use this calculator inside a step-by-step guide.
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