Purposeful FIRE💰401(k) Growth Calculator
Project your 401(k) balance at retirement including employer match, salary growth, and compounding. See exactly how much of your final balance comes from your contributions, your employer, and investment returns.
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What Is 401(k) Growth?
Your 401(k) is the most powerful forced-savings mechanism most employees have access to. Contributions come out before you see them, reduce your taxable income today, and grow tax-deferred until retirement. The employer match, when one exists, is the highest guaranteed return available in personal finance: a 100% match on the first 3% of your salary means a 100% return before the market even opens.
This calculator models all the moving parts together: your current balance, your contribution rate, your employer's match formula, salary growth over time, expected investment returns, and years to retirement. The result breaks down exactly how much of your final balance came from you, your employer, and compound growth, which often surprises people who underestimate how much of their eventual wealth will be returns rather than contributions.
How This Calculator Works
Each year the model grows your existing balance by the expected return, adds your contribution (your salary for that year times your contribution percentage), and adds the employer match (your contribution, up to the match cap expressed as a percentage of salary, multiplied by the match rate). Salary grows by the salary growth rate each year. The result compounds year over year.
Personal Considerations
The most common 401(k) mistake is contributing exactly the match cap and stopping there. The match is not the ceiling of what you should save; it's the floor below which you're leaving guaranteed compensation on the table. Once you've captured the full match, continue increasing your contribution rate until you hit the IRS limit or your FIRE savings target.
Seeing the three-way breakdown of your projected balance, your contributions, your employer's contributions, and investment growth, makes the case for starting early more viscerally than any abstract rule about compound interest. Most people who start early will find that investment growth eventually dominates the balance, often comprising 50% or more of the final number. That is the payoff for patience.
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Frequently Asked Questions
If your employer offers both, the traditional 401(k) lowers your tax bill today (valuable if you're in a high bracket now), while the Roth 401(k) grows tax-free (valuable if you expect to be in a high bracket in retirement, or if you want tax diversification). Many FIRE adherents use a mix to give themselves withdrawal flexibility later.
Set the employer match rate to 0%. The calculator still models the growth of your own contributions and salary over time. Without a match, a Roth IRA (up to $7,000/year in 2024) may be worth maxing first since it offers more investment options and more flexible withdrawal rules.
The calculator uses the percentage you enter and does not automatically cap at the IRS limit. If your salary times your contribution percentage would exceed the IRS limit, you should enter a lower percentage to reflect what you'll actually contribute in years where the limit binds.
A diversified stock/bond portfolio has historically returned 6-8% annualized over long periods after inflation. For a 20-30 year horizon, 7% is a common planning assumption. Use 5-6% if you want to be conservative, or model both to see the range.