401(k) Calculator: How Much Will You Have at Retirement?

A 401(k) is the most powerful retirement savings tool available to American workers. It reduces your taxable income today, grows tax-deferred for decades, and is often topped up with free money from your employer. Yet most people contribute without ever modelling where they will actually end up at retirement.

This guide explains the current 2026 IRS rules, how employer matching works, and how to use our calculator to project your exact retirement balance.

2026 IRS 401(k) Contribution Limits

The IRS adjusts limits annually. For 2026:

The employee deferral limit increased from $23,500 (2025) to $24,500 (2026). The sidebar on many calculators still shows the old $23,000 figure from 2024 — make sure yours is up to date.

The SECURE 2.0 Super Catch-Up for Ages 60–63

Starting in 2025, workers aged exactly 60, 61, 62, or 63 can contribute $11,250 in catch-up contributions — rather than the standard $8,000 for other 50+ employees. This is one of the most underused provisions in retirement planning. Turning 60 and knowing you can shelter $35,750 per year (before employer match) in one year can make a significant difference to your final balance.

The Compensation Cap: What High Earners Must Know

The IRS caps the salary used to calculate your contributions and your employer's match at $360,000 for 2026. If you earn $500,000, your employer calculates matching on $360,000 — not $500,000. This surprises many high earners who assume the match is uncapped.

How Employer Matching Works

Employer matching is the highest guaranteed return available anywhere. A typical match of "50% of contributions up to 6% of salary" works like this:

• You earn $80,000 and contribute 6% → $4,800/year
• Employer contributes 50% of that → $2,400/year
• Before any investment return, you immediately have 50% more

Always contribute at least enough to capture the full employer match. Leaving it unclaimed is refusing part of your salary.

Common Match Structures

Traditional vs Roth 401(k)

How Compound Growth Works in a 401(k)

A 30-year-old earning $75,000 contributing 10% ($7,500/year) with a 50% employer match on 6% ($2,250/year) at 7% annual return:

The difference between starting at 30 vs 40 is roughly $590,000 at retirement — for the same contribution rate.

The 4% Rule: How Much Income Will You Have?

The 4% rule estimates sustainable annual withdrawals from a retirement portfolio. Withdraw 4% in year one, then adjust for inflation each year — with high historical confidence the portfolio survives 30 years.

Morningstar's 2025 research recommends 3.9% for new retirees today; Bengen (the rule's creator) updated his figure to 4.7% in 2025 based on more diversified allocations.

Key Rules to Avoid Costly Mistakes

1. Early withdrawal penalty — Taking money before age 59½ triggers a 10% penalty plus income tax. A $50,000 early withdrawal can cost $20,000+ in taxes and penalties.
2. Required Minimum Distributions — Traditional 401(k) holders must start withdrawals at age 73. Missing an RMD triggers a 25% penalty on the missed amount.
3. Vesting schedules — Employer matching may vest over 2–6 years. Leaving before full vesting means forfeiting unvested employer contributions.
4. Excess contributions — Must be corrected by 15 April of the following year. Uncorrected excess is taxed twice.

5 Strategies to Maximise Your 401(k)

1. Capture the full employer match first — this is always priority one.
2. Increase your contribution by 1% each time you receive a pay rise.
3. If you are 60–63, use the SECURE 2.0 super catch-up — $11,250 extra per year.
4. Choose low-cost index funds — target-date funds typically outperform active funds net of fees over 20+ years.
5. Roll over old 401(k)s from previous employers — don't leave money fragmented across five old plans.