401K Calculator

RETIREMENT TOOLS

401(k) Calculator

Project your 401(k) balance at retirement based on your contributions, employer match, and expected investment growth.

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PROJECTED BALANCE AT RETIREMENT
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Your annual contribution$0
Employer match (annual)$0
Total contributed over time$0
Total investment growth$0
Disclaimer: This calculator provides estimates for informational and educational purposes only and does not constitute financial or investment advice. It assumes a constant contribution rate, flat salary, and steady annual return, which real investments don't provide. Consult a financial advisor for personalized retirement planning.

401K Calculator: Formula, Worked Examples & Complete Guide

Written by Mathew | Financial Tools & Calculation Specialist · Last updated August 01, 2026

In two sentences: A 401k calculator projects your retirement account balance by compounding regular contributions and employer matching over time, using the 2026 contribution limits of $24,500 for employees under 50, plus an $8,000 catch-up for those 50 and older. This guide breaks down the compound growth formula, current IRS limits, and worked examples showing exactly how contribution timing and employer match affect your final balance.

What Is a 401K Calculator?

A 401k calculator projects the future value of your retirement account based on your current balance, ongoing contributions, employer match, expected investment return, and time horizon until retirement. Because 401(k) growth compounds over decades, small differences in contribution rate or starting age can produce dramatically different outcomes by retirement.

The 401K Calculator Formula

Future Value = P(1 + r)^n + C × [((1 + r)^n − 1) ÷ r]

P = current balance
r = expected annual rate of return
n = number of years until retirement
C = annual contribution (including any employer match)

This combines the growth of your existing balance with the compounding growth of a series of regular annual contributions — the same structure used for any long-term savings projection.

2026 401(k) Contribution Limits

The 401(k) contribution limit for 2026 is $24,500 for employee salary deferrals, up from $23,500 in 2025. The combined employee-and-employer contribution limit is $72,000 for 2026. If you’re age 50 or older, you can make an additional catch-up contribution of $8,000, bringing your total employee contribution limit to $32,500. For employees ages 60 through 63 specifically, a higher “super catch-up” contribution of $11,250 applies instead of the standard $8,000, under a provision from the SECURE 2.0 Act.

A new rule for high earners starting in 2026

Starting in 2026, higher earners who made more than $150,000 in the prior year must make catch-up contributions on a Roth (after-tax) basis in employer-sponsored plans, rather than being able to choose pre-tax catch-up contributions as in previous years.

Worked Examples

Example 1: Basic compound growth without contributions

A 40-year-old with a $100,000 balance, no further contributions, expecting a 7% average annual return until retirement at 65 (25 years).

Future Value = $100,000 × (1.07)^25 ≈ $100,000 × 5.427 ≈ $542,700

Example 2: Adding regular contributions

The same 40-year-old, now contributing $15,000/year (including any employer match) alongside the existing $100,000 balance, at 7% return over 25 years.

Growth of existing balance: $100,000 × (1.07)^25 ≈ $542,700
Growth of contributions: $15,000 × [((1.07)^25 − 1) ÷ 0.07] ≈ $15,000 × 63.25 ≈ $948,750
Total Future Value ≈ $542,700 + $948,750 ≈ $1,491,450

Notice the ongoing contributions ultimately contribute nearly twice as much to the final balance as the original lump sum — a clear illustration of why consistent contributions matter as much as, or more than, your starting balance.

Example 3: The impact of starting 10 years earlier

Compare a worker starting to contribute $10,000/year at age 25 versus age 35, both retiring at 65, at a 7% return.

Starting at 25 (40 years): $10,000 × [((1.07)^40 − 1) ÷ 0.07] ≈ $10,000 × 199.64 ≈ $1,996,400
Starting at 35 (30 years): $10,000 × [((1.07)^30 − 1) ÷ 0.07] ≈ $10,000 × 94.46 ≈ $944,600

The 10-year head start, with identical annual contributions, produces more than double the final balance — a direct result of compounding having a full extra decade to work.

Example 4: Maximizing the catch-up contribution

A 62-year-old using the 2026 super catch-up provision, contributing the full $24,500 base plus $11,250 super catch-up ($35,750 total), for 5 years until retirement at 67, at a 6% return.

Future Value of contributions = $35,750 × [((1.06)^5 − 1) ÷ 0.06] ≈ $35,750 × 5.637 ≈ $201,523

Just 5 years of maximum super catch-up contributions can add over $200,000 to a retirement balance, showing why this provision matters significantly for late-career savers approaching retirement.

Step-by-Step: How to Use a 401K Calculator

  1. Enter your current 401(k) balance.
  2. Enter your planned annual contribution, including any employer match — remember employer match doesn’t count against your personal $24,500 limit, but does count toward the combined $72,000 limit.
  3. Enter your expected average annual rate of return (7% is a commonly used long-term historical estimate for a diversified stock-heavy portfolio, though actual returns vary).
  4. Enter your number of years until retirement.
  5. Review the projected future value, and try adjusting contribution amount or retirement age to see the sensitivity of your final balance to each variable.

Why Employer Match Is “Free Money” Worth Maximizing

Many employers match a percentage of employee contributions, commonly up to a certain percentage of salary. Since employer match contributions don’t count against your personal $24,500 employee deferral limit — only against the higher combined $72,000 limit — failing to contribute enough to capture your full employer match is effectively leaving free money on the table. A 401k calculator that separates your own contributions from employer match makes this gap concretely visible in dollar terms over a full career.

Using a 401K Calculator to Optimize Your Contribution Strategy

A 401k calculator becomes especially valuable when it’s used to test specific contribution decisions, not just to admire a distant future balance.

Practical ways to use a 401K calculator

  • Find the true cost of delaying enrollment. A 401k calculator comparing someone who starts contributing immediately against someone who waits even a few years shows concretely how much permanent balance is lost to missed compounding, which is often more persuasive than a general recommendation to “start early.”
  • Test whether increasing your contribution rate by 1% matters. Small percentage increases feel negligible in a single paycheck, but a 401k calculator run over a full career shows how even a 1% bump in contribution rate can add tens of thousands of dollars by retirement.
  • Model the catch-up and super catch-up provisions for late-career savers. For anyone 50 and older, a 401k calculator that separately accounts for the standard $8,000 catch-up or the $11,250 super catch-up (ages 60-63) shows exactly how much these provisions can accelerate a shortfall.
  • Compare traditional versus Roth contributions under different tax assumptions. A 401k calculator can help illustrate how the choice between pre-tax and after-tax contributions plays out differently depending on whether you expect your tax rate to be higher or lower in retirement.

Frequently Asked Questions

What’s the difference between a traditional and Roth 401(k)?

Traditional 401(k) contributions are made pre-tax, reducing your current taxable income, with withdrawals taxed in retirement. Roth 401(k) contributions are made after-tax, with qualified withdrawals in retirement being completely tax-free — the 2026 contribution limits are the same for both types.

Does the $72,000 combined limit include catch-up contributions?

The catch-up contribution generally applies on top of the standard combined limit for eligible savers 50 and older, allowing total contributions to exceed the base $72,000 figure specifically through catch-up provisions.

Is 7% a realistic long-term return assumption for a 401(k) calculator? I

It’s a commonly used estimate based on long-term historical stock market averages, but actual returns vary significantly year to year and depend heavily on your specific investment allocation — a calculator’s projection should be treated as an illustrative estimate, not a guarantee.

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

This depends on your specific financial situation, but a common baseline recommendation is contributing at least enough to capture your full employer match, then increasing contributions toward the annual limit as your budget allows.

Related Calculators

In summary, a 401k calculator shows how consistent contributions and time in the market compound into meaningful retirement savings, and understanding the 2026 contribution limits — including the valuable catch-up and super catch-up provisions — helps you make the most of every dollar of tax-advantaged retirement saving available to you.

About the author: Mathew is a Financial Tools & Calculation Specialist focused on building and fact-checking online calculators across retirement planning and personal finance topics.

Note: This calculator and article are provided for general educational and informational purposes only and do not constitute financial or investment advice. Contribution limits are set by the IRS and subject to annual change. Investment returns are not guaranteed. Consult a qualified financial advisor for personalized retirement planning.