401(k) Calculator

What this calculator does

This calculator projects your 401(k) balance from today through your retirement age, accounting for your contributions, your employer's match, salary growth, and investment returns. It enforces the 2025 IRS employee deferral limit ($23,500) and lets you see exactly how much of your final balance came from your contributions, employer match, and compound growth.

How an employer match works

Most matches are described in two pieces: a rate and a cap. A common formula is “100% match up to 6% of salary,” meaning the employer contributes one dollar for every dollar you do, up to a maximum of 6% of your salary. If you only contribute 3%, the employer only matches 3%. This is why every personal-finance article tells you to “at least get the match” — leaving it on the table is a guaranteed pay cut.

The three engines of growth

1. Your contributions. Pre-tax payroll deductions — you don't pay federal income tax on them today.
2. Employer match. Free money. The fastest way to accelerate your balance.
3. Compound growth. Your balance earns returns, and those returns earn returns. After 20+ years, this is usually the largest piece of the final balance.

A worked example

At age 30 with $10k in your 401(k), an $80k salary, 8% employee contribution, 100% match up to 6%, 2.5% annual salary growth, and 7% return, the model projects roughly $2 million at age 65. About $400k comes from your contributions, $300k from the employer match, and the rest — over $1.3M — from compound growth.

Tips and common mistakes

• Always capture the full match. If you contribute less than the match cap, you're leaving guaranteed money behind.
• Increase contributions when you get raises. Bumping your contribution by 1% with each raise is nearly painless and dramatically increases your final balance.
• Watch fees. A 1% expense ratio compounds against you the same way returns compound for you. Look for low-cost index funds in your plan.
• Don't cash out when you leave a job. Cashing out triggers income tax plus a 10% early-withdrawal penalty under age 59½. Roll to an IRA or your new employer's 401(k) instead.

Frequently asked questions

How much should I contribute to my 401(k)?

At minimum, contribute enough to capture the full employer match — that's an instant, guaranteed 50–100% return on those contributions. Beyond that, common targets are 10–15% of gross income (including the match). The IRS 2025 employee deferral limit is $23,500 ($31,000 with the age-50+ catch-up).

What is vesting?

Vesting is the schedule on which employer match contributions become yours to keep. Employee contributions are always 100% vested immediately. Employer contributions might vest immediately, on a cliff (e.g. 100% after 3 years), or gradually (e.g. 20% per year over 5 years). If you leave before fully vesting, you forfeit the unvested portion. Check your plan documents.

Should I do Roth 401(k) or traditional?

Traditional contributions are pre-tax — they lower your current taxable income but you pay tax on withdrawals in retirement. Roth contributions are after-tax — no current deduction but withdrawals are tax-free. Rule of thumb: traditional if your tax rate now is higher than you expect in retirement; Roth if lower. Many people split contributions between the two for tax diversification.

What happens to my 401(k) when I leave my job?

You have four options: (1) leave it with your old employer's plan if allowed, (2) roll it into your new employer's 401(k), (3) roll it into an IRA, or (4) cash it out (this triggers tax + a 10% penalty if under age 59½ — almost never the right move). Rolling to an IRA usually gives you the most investment options and lowest fees.

How does the IRS contribution limit work?

The 2025 employee deferral limit is $23,500 across all 401(k) plans you contribute to in a year. If you have multiple jobs, you can't double-dip. Workers age 50+ can contribute an additional $7,500 catch-up. Employer match contributions don't count against this limit but do count against a higher combined limit ($70,000 in 2025).

What if my employer doesn't offer a match?

Even without a match, a 401(k) is still a strong vehicle: pre-tax contributions lower current taxes, and growth is tax-deferred (or tax-free in a Roth). With no match, an IRA can be a useful alternative since it typically has more investment options. Maxing both an IRA and a 401(k) is the strongest play if cash flow allows.