401k Calculator

Project your 401k balance at retirement with employer match and compound growth.

🏦 What is a 401k?

A 401k is a tax-advantaged retirement savings plan sponsored by employers in the United States, named after the section of the Internal Revenue Code that governs it. Employees elect to have a portion of their pre-tax paycheck deposited directly into their 401k account, where it grows tax-deferred until retirement. This tax deferral is one of the most powerful features of a 401k - you don't pay taxes on contributions or investment gains until you withdraw the money in retirement, allowing your full contribution to compound over decades.

Most employers offer a matching contribution as a benefit, where the company adds money to your 401k based on how much you contribute. A typical employer match is 50% of your contribution up to 6% of your salary - effectively increasing your compensation. Failing to contribute enough to capture the full match is often described as "leaving free money on the table." The 2024 employee contribution limit is $23,000, with a $7,500 catch-up for those 50 and older.

At retirement (age 59½ or later), withdrawals are taxed as ordinary income. Many retirees are in a lower tax bracket than during their working years, making the tax deferral even more beneficial. The 401k is the cornerstone of retirement savings for millions of Americans, often supplemented by an IRA or Roth IRA for additional tax-advantaged space.

📐 401k Growth Formula

FV = B × (1+r)ⁿ + C × [((1+r)ⁿ − 1) / r] × (1+r)

FV = Final balance at retirement

B = Current 401k balance

C = Annual contribution (your contributions + employer match)

r = Annual return rate (e.g., 0.07 for 7%)

n = Years until retirement

The formula combines two components: the growth of your existing balance (a lump-sum future value) and the accumulation of annual contributions (an annuity-due). Total annual contribution = (Salary × Your %) + min(Salary × Your %, Salary × Match Cap) × Match%. The result is the projected 401k balance at your target retirement age. Monthly income is estimated using the 4% rule: divide the balance by 25 to get annual sustainable withdrawal.

📖 How to Use This Calculator

Steps

Enter your annual salary - use your current gross (pre-tax) annual salary.

Set your contribution rate - the percentage of your salary you contribute each paycheck. The IRS limit for 2024 is $23,000.

Enter employer match details - the match percentage (e.g., 50%) and the salary cap up to which they match (e.g., 6%).

Enter your current balance and age - include any existing 401k balance and your current and target retirement age.

Click Calculate - see your projected balance, total contributions, employer contributions, and estimated monthly retirement income.

💡 Example Calculations

Example 1 - 30-Year-Old Starting with $10,000

Salary = $80,000 | Contribution = 6% | Match = 50% up to 6% | Balance = $10,000 | Age 30→65 | Return = 7%

Your annual contribution = $80,000 × 6% = $4,800

Employer match = 50% × $4,800 = $2,400/year

Total annual contribution = $4,800 + $2,400 = $7,200/year

FV of existing $10,000 over 35 years at 7% = $10,000 × (1.07)³⁵ = $107,613

FV of $7,200/year annuity over 35 years = $7,200 × [(1.07³⁵ - 1)/0.07] × 1.07 = $1,038,450

Total Balance = $107,613 + $1,038,450 = $1,146,063 | Monthly Income (4% rule) = $3,820/month

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Example 2 - Aggressive Saver, Age 40

Salary = $120,000 | Contribution = 15% | Match = 100% up to 4% | Balance = $150,000 | Age 40→62 | Return = 7%

Your annual contribution = $120,000 × 15% = $18,000 (capped at IRS limit $23,000 - within limit)

Employer match = 100% × min($18,000, $120,000 × 4%) = 100% × $4,800 = $4,800

Total annual = $22,800 | FV of $150,000 over 22 years at 7% = $700,254

FV of $22,800 annuity over 22 years + $700,254 = ~$1,885,000 | Monthly Income = $6,283/month

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❓ Frequently Asked Questions

What is a 401k plan and how does it work?+

A 401k is an employer-sponsored defined-contribution retirement savings plan in the United States. Employees contribute a percentage of their pre-tax salary each paycheck; the money grows tax-deferred until withdrawal in retirement. Many employers match a portion of contributions - for example, 50% of the first 6% of salary - which is effectively free money. Contributions reduce your taxable income today, and you pay ordinary income tax only when you withdraw in retirement.

What is the 401k contribution limit for 2024?+

The IRS 401k contribution limit for 2024 is $23,000 for employee contributions. Workers aged 50 and older can make an additional catch-up contribution of $7,500, bringing the total to $30,500. Employer contributions do not count toward the employee limit, but the combined employer + employee contribution cannot exceed $69,000 (or $76,500 with catch-up) in 2024.

How does employer matching work in a 401k?+

Employer matching is when your company adds money to your 401k based on your own contributions. A common formula is '50% match on up to 6% of salary' - if you earn $80,000 and contribute 6% ($4,800), your employer adds 50% of that ($2,400). Some employers offer a 100% match up to 3–4% of salary. You must contribute at least the match threshold to receive the full match.

When can I withdraw from my 401k without penalty?+

You can withdraw from your 401k penalty-free at age 59½. Withdrawals before 59½ are subject to a 10% early withdrawal penalty plus ordinary income tax. Required Minimum Distributions (RMDs) must begin at age 73. There are exceptions to the penalty: substantially equal periodic payments (Rule 72t), disability, certain medical expenses, and separation from service at age 55.

What rate of return should I use for 401k projections?+

The S&P 500 has historically returned about 10% annually before inflation (7% real). For conservative 401k planning, most financial planners use 6–7% (after inflation). Use 8–10% for an optimistic scenario and 5–6% for conservative. Your actual return depends on your fund allocation - an all-equity portfolio has historically outperformed bonds over 20+ year horizons but with more volatility.

What is a good 401k balance by age?+

Fidelity's rule of thumb: save 1x salary by 30, 3x by 40, 6x by 50, 8x by 60, and 10x by 67. For example, if you earn $75,000, the target is $75,000 by 30, $225,000 by 40, $450,000 by 50, $600,000 by 60, and $750,000 by retirement. These are benchmarks and depend heavily on when you start contributing and your income growth.