401k Calculator

How to use this calculator

Enter your current age, retirement age, current annual salary, current 401k balance, employee contribution rate, employer match percentage, match cap (maximum % of salary your employer will match), and expected annual return.

The calculator shows your projected 401k balance at retirement, your monthly income using the 4% rule, total employer contributions over your career, and investment growth. The match capture rate tells you what percentage of the available employer match you’re actually getting.

Employer Match Rate is the percentage of your contribution your employer matches. A “50% match” means for every dollar you put in, your employer adds $0.50.

Match Up To is the cap. A plan that matches “50% up to 6% of salary” means contributions beyond 6% of your salary don’t get matched. Enter 6 in this field.

How 401k math works

A 401k compounds monthly. Both your contributions and your employer’s match go in each month, and the whole balance grows at the market return rate.

The employer match adds $2,400/year. Over 35 years at 7%, that $2,400/year compounds to $348,000. Your employer effectively contributes $348,000 to your retirement — 18% of the final balance.

The cost of missing the employer match

Missing the employer match is the most expensive financial mistake most employees make. Here’s what leaving the full match on the table costs:

On an $80,000 salary with a 50% match up to 6%: the maximum employer match is $2,400/year. Over 35 years at 7%, that’s $348,000 in lost retirement savings. Just from not contributing the extra few percent of salary.

The effective return on contributions up to the match threshold is dramatic:

Before paying down low-interest debt, before extra mortgage payments, before taxable investing — capture the full employer match. No other investment offers a guaranteed 50-100% return on day one.

Traditional 401k vs Roth 401k

Most employers offer both. The choice affects when you pay taxes.

A 30-year-old earning $60,000 in the 22% bracket who expects to retire with $90,000 in income (also 22%) mathematically comes out the same either way. The uncertainty is which way taxes move.

One practical strategy: split contributions — enough Traditional to get the employer match, then Roth on additional contributions. Employer matches always go into the traditional side regardless of which you choose.

2025 contribution limits in detail

The IRS caps 401k contributions annually:

The $23,500 employee limit is per person, per year — if you contribute to two different 401k plans (say, at two jobs or a solo 401k), the combined total can’t exceed $23,500.

Employer contributions don’t count toward the $23,500 employee limit, but do count toward the $70,000 total. This matters mainly for high earners who also have profit-sharing contributions from their employer.

Vesting: when employer contributions become yours

Your own contributions are always 100% yours immediately. Employer contributions typically vest over time.

Immediate vesting: Employer match is yours from day one. Increasingly common.

3-year cliff vesting: You get 0% of the employer match if you leave before 3 years, 100% after. Common in smaller plans.

Graded vesting (6-year): 20% per year starting at year 2. At year 6, fully vested.

If you have $12,000 in employer contributions after 2 years with a 3-year cliff, leaving means forfeiting all $12,000. After 3 years, you keep it all. Vesting schedules should absolutely factor into job change timing.

Check your Summary Plan Description (SPD) to find your plan’s exact vesting schedule.

Investment choices inside a 401k

You can’t pick individual stocks in most 401k plans. You choose from a menu of funds — usually 10-30 options. The right approach: find the lowest-cost index funds on the menu.

What to look for:

• Total expense ratio under 0.1% (index funds from Vanguard, Fidelity, Schwab)
• Broad market coverage: US total market, international, bonds
• Avoid target-date funds unless their expense ratio is under 0.15% — many are overpriced

A 1% expense ratio vs 0.05% on a $500,000 balance costs you roughly $5,000/year in fees. Over 20 years, that’s $100,000+ in unnecessary charges — money that would have compounded in your account instead.

If your plan only offers expensive options, put your money in the least-bad option, capture the match, and invest additional savings in a Roth IRA with access to Vanguard or Fidelity’s full fund catalog.

What to do if you’re behind

The Fidelity benchmarks: 1x your salary saved by 30, 3x by 40, 6x by 50, 8x by 60.

At 45 earning $90,000 with $200,000 saved, you’re short of the 3x benchmark. The gap to 6x by 50 is $340,000. Closing it completely in 5 years requires roughly $4,500/month in new contributions — steep.

A more realistic path: maximize catch-up contributions at 50 ($31,000/year), cut unnecessary expenses to increase the savings rate, and consider working 2-3 years longer than originally planned. Those extra years do three things simultaneously: reduce the required portfolio (shorter retirement to fund), add contributions, and add compounding time.

At $31,000/year in contributions for 15 years (age 50 to 65) at 7% return, starting from $200,000, you reach $1.5M — enough for $60,000/year at the 4% rule. Catching up is possible. It just requires aggressive contributions in the final decade.

The 401k withdrawal strategy in retirement

How you withdraw from a 401k in retirement matters as much as how you saved.

The 4% rule is a starting point, not a rigid formula. Draw 4% in good years, 3-3.5% when markets are down. This flexibility significantly improves portfolio longevity.

Order of withdrawals: Draw from taxable accounts first (long-term capital gains rates), then Traditional 401k/IRA (ordinary income), then Roth last (tax-free). This extends the tax-free growth on Roth assets and controls taxable income in the early retirement years.

RMDs start at 73 for Traditional 401k accounts. The calculation forces withdrawals whether you need them or not, potentially pushing you into higher brackets. Roth conversions in your early 60s — while income is typically lower than working years but before RMDs kick in — can reduce the eventual RMD burden.

A $1M Traditional 401k at age 73 requires a first RMD of roughly $37,700. That’s taxable income on top of whatever else you’re drawing. Converting $50,000/year to a Roth between 62-72 could cut that eventual RMD in half.