A 401(k) is the single most powerful retirement tool most American workers have, largely because of two forces this 401(k) calculator makes visible: employer matching and decades of tax-deferred compounding. Enter your salary, the percentage you contribute, your employer's match terms, and your expected return, and the calculator projects your balance at retirement in real time — splitting the result into your own contributions, your employer's match, and pure investment growth. The interactive chart shows how, over a full career, market growth typically ends up dwarfing the money you actually put in, which is exactly why starting early matters more than contributing heroically later.
401(k) Calculator
Finance
Project your 401(k) balance at retirement with employer match
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Why 401(k) Calculator Matters
Roughly a quarter of employees don't contribute enough to capture their full employer match — which is a guaranteed, instant 25–100% return left on the table every payday. Seeing the match quantified in dollars over 25 or 30 years usually settles the question of whether to prioritize it. The calculator also makes trade-offs concrete: bumping contributions from 6% to 10% of an $80,000 salary costs about $267 per month today but can add several hundred thousand dollars by retirement. For 2026, the IRS employee deferral limit is $24,500, with an additional catch-up contribution allowed for those 50 and older.
The 401(k) Calculator Formula, Explained
FV = Σ monthly deposits × (1 + r/12)^(months remaining)Each month, your contribution plus the employer match is added to the balance, and the whole balance grows by the monthly return (annual rate ÷ 12). The employer match equals your salary × the matched share of pay (up to the match limit) × the match rate — for example, '50% up to 6%' on an $80,000 salary is $80,000 × 6% × 50% = $2,400 per year. If you enter salary growth, contributions rise each year with your pay.
How to Use the 401(k) Calculator: Step by Step
Enter your current annual salary before tax
Enter your current annual salary before tax.
Set your contribution as a percentage of salary
Set your contribution as a percentage of salary — the slider makes it easy to test different rates.
Enter your employer's match rate (e
Enter your employer's match rate (e.g., 50 means 50 cents per dollar) and the match limit as a percent of salary (commonly 3–6%).
Add your current 401(k) balance and expected annual return (
Add your current 401(k) balance and expected annual return (7% is a common long-run assumption for a stock-heavy portfolio).
Set years until retirement, and optionally add annual salary
Set years until retirement, and optionally add annual salary growth under Advanced options.
Read the projected balance and check the chart to see contri
Read the projected balance and check the chart to see contributions versus investment growth over time.
401(k) Calculator Examples: Real-World Scenarios
1
Full match captured
Salary $80,000, contributing 10%, employer matches 50% up to 6% of salary, $0 starting balance, 7% return, 25 years.
Annual salary:$80,000
Contribution:10%
Match:50% up to 6%
Return:7%
Years:25
Calculation
You contribute $8,000/year and the employer adds $80,000 × 6% × 50% = $2,400/year — $10,400 total, about $867/month. At 7% compounded monthly for 25 years this grows to roughly $702,000, of which only $260,000 is contributions; the rest is growth.
Result
≈ $702,000 at retirement
2
The cost of skipping the match
Same worker contributes only 3%, so the employer matches just 3% (50% × 3% = 1.5% of salary).
Annual salary:$80,000
Contribution:3%
Match:50% up to 6%
Return:7%
Years:25
Calculation
Contributions fall to $2,400 + $1,200 = $3,600/year ($300/month), growing to roughly $243,000 over 25 years — about $459,000 less, of which roughly $91,000 is match money simply forfeited plus its lost growth.
Result
≈ $243,000 — less than half the full-match outcome
3
Starting with a balance
Age 40 with $150,000 saved, salary $100,000, contributing 12% with a 4% full match, 6.5% return, 25 years to go.
Current balance:$150,000
Salary:$100,000
Contribution:12%
Match:100% up to 4%
Return:6.5%
Years:25
Calculation
The existing $150,000 alone compounds to about $757,000. Contributions of $16,000/year (~$1,333/month) add roughly another $1,000,000, for a combined total in the $1.75M range.
Result
≈ $1.75 million at 65
Common Mistakes to Avoid
- Contributing less than the full employer match — it is the highest-return 'investment' available anywhere.
- Using an overly optimistic return (10%+) for planning; 6–7% nominal is a more defensible long-run assumption for a diversified portfolio.
- Ignoring the IRS deferral limit when modeling high contribution percentages on large salaries.
- Forgetting that this projection is pre-tax: traditional 401(k) withdrawals are taxed as ordinary income in retirement.
- Cashing out when changing jobs instead of rolling over — early withdrawal typically triggers income tax plus a 10% penalty.
Tips & Tricks
- Increase your contribution by 1% each year or whenever you get a raise — you will barely feel it in take-home pay.
- If your plan offers a Roth 401(k) option, contributions are after-tax but withdrawals are tax-free; young or lower-bracket workers often benefit.
- Check your plan's vesting schedule — employer match money may only become fully yours after several years of service.
- Target-date funds are a reasonable one-decision default if you don't want to manage allocation yourself.
- Rerun this calculator annually with your real balance to keep your plan honest.
A 401(k) projection is mostly a story about time, consistency, and free match money. Capture the full match, pick a sane return assumption, and let the chart show you why the growth curve steepens dramatically in the final decade — that's compounding doing the heavy lifting.
401(k) Calculator — Frequently Asked Questions
Related Calculators
Authoritative References
IRS — 401(k) plans overview
irs.gov — Authoritative reference
U.S. Department of Labor — retirement savings
dol.gov — Authoritative reference
External links open in a new tab. OmniCalc.us is not affiliated with these organisations.