About the 401(k) Calculator
A 401(k) is the backbone of US retirement saving: pre-tax contributions, automatic investing in the plan menu, and — the part many people underestimate — employer matching dollars that more than double your savings rate when you hit the full match.
This tool projects your ending balance from today: your current balance keeps compounding, your contributions and your employer’s match flow in monthly, and the total grows at your expected return.
The formula behind it
Match, then compound:
Employer match = min(your contribution, salary × match-max%) × match-% • FV =Balance×(1+r)^y + contributions/mo × annuity factorThe match formula is the standard “50% of every dollar, up to 6% of pay” structure (enter your plan’s actual numbers). The FV leg grows the existing balance and the level monthly flow of contributions plus match at r/12 per month.
Worked example
Defaults — $50,000 balance, $70,000 salary, $6,000/yr contributed, 50% match to 6%, 25 years at 7%:
- Employer match = min($6,000, $70,000×6% = $4,200) × 50% = $2,100/yr.
- Total annual inflow = $8,100 ($675/month) on top of the $50,000 base.
- The base alone grows to about $271,400; the monthly flow compounds to roughly $512,000.
Takeaway: Projected ending balance ≈ $784,000 — while total contributions over the 25 years are just $150,000 plus $52,500 of match. Compounding contributes over half the pot.
What moves the result
- Contribution rate — 2026 elective deferral limit is $24,500 ($32,500 for age 50+); going from 6% to 10% of pay changes retirement a great deal.
- Employer match — a full match is the fastest available dollars in investing; anything less than the full match is a raise you are declining.
- Years to grow — time, not cleverness, does the compounding.
- Expected return — plan-menu expense ratios run 0.1–1.0%+; the low-fee options change decades of compounding.
Practical tips
- Contribute at least to the full employer match — this is the money in the room no other investment ranks above.
- Check your plan’s vesting schedule; changing jobs too early can cost dollars you forgot you earned.
- Watch fees inside the menu: a fund at 0.9%/yr on the same return costs tens of thousands across a career vs an index option.
- A 401(k) loan is sometimes familiar but be careful — a job change can trigger forced repayment at the worst time.
- The IRS "catch-up" additions at 50 ($8,000 in 2026) and 60–63 ($11,250) can re-accelerate a late-career sweep.
Frequently asked questions
What is the 2026 401(k) contribution limit?
$24,500, plus $8,000 catch-up if you are 50+ (and $11,250 for ages 60–63, per SECURE 2.0). Source page below links the IRS announcement.
Does employer match count toward my 24,500?
No — the employee deferral limit is yours alone. Combined employee+employer limits allow up to $72,000 for 2026 (the annual additions cap).
Traditional or Roth 401(k)?
Traditional lowers your taxable income now; Roth is taxed on the way in and tax-free qualified later. A balancer: smaller-tax-bracket circumstances guide arguments; compare both and mix if your plan supports it.