What Is a 401(k) Calculator?
A 401(k) calculator is an interactive financial planning tool that projects how much money you may have saved by the time you reach retirement age. It models the compounding interaction between your current account balance, ongoing employee paycheck deferrals, employer matching contributions, assumed market returns, and the time horizon until your planned retirement date.
By simulating variables such as salary increases, inflation rates, and investment expense ratios, our 401(k) growth calculator enables you to test "what-if" scenarios. It clarifies whether your current savings rate puts you on track to meet your retirement income goals or whether minor adjustments—such as increasing contributions by 1% or capturing your complete employer match—could significantly expand your nest egg.
2026 401(k) Contribution Limits
The Internal Revenue Service (IRS) establishes statutory limits each tax year under the Internal Revenue Code to govern maximum allowable contributions to defined-contribution retirement plans. For tax year 2026, the elective deferral limit for employees participating in 401(k), 403(b), and most 457 plans is $24,500.
| Contribution Category | 2026 IRS Limit |
|---|---|
| Employee Elective Deferrals (under age 50) | $24,500 |
| Standard Catch-Up Contribution (ages 50–59, 64+) | $8,000 |
| Enhanced Catch-Up Contribution (ages 60, 61, 62, 63 under SECURE 2.0) | $11,250 |
| Total Combined Additions (Employee Deferrals + Employer Contributions) | $72,000 |
| Annual Compensation Limit for Plan Contributions (IRC 401(a)(17)) | $360,000 |
Note on 2026 Roth Catch-Up Rule: Beginning in 2026, certain participants who make catch-up contributions may be required to make those catch-up contributions on a Roth basis. For 2026 contributions, the rule generally applies when the participant's 2025 FICA wages from the employer sponsoring the plan exceeded $150,000.
This rule applies specifically to catch-up contributions and does not mean all regular 401(k) contributions must be Roth. The $150,000 figure is a prior-year wage threshold used to determine whether the Roth catch-up requirement applies; it is not a 401(k) contribution limit. Plan implementation and individual circumstances can vary.
How Does a 401(k) Employer Match Work?
An employer 401(k) match is an incentive program where your company contributes additional funds to your retirement account based on your own contributions up to a predefined limit. Employer matching contributions can significantly increase the amount being added to your retirement account, subject to your plan's matching formula, eligibility requirements, and vesting rules.
The most prevalent matching structure is a partial match, commonly 50% of your contributions up to 6% of your salary. For example, if you earn $75,000 annually and contribute 6% ($4,500), your employer contributes 50% of that amount ($2,250), bringing your total annual 401(k) additions to $6,750. If you contribute less than 6% (for instance, 4%), you receive only $1,500 in matching funds and leave $750 in potential employer contributions unclaimed.
Other employers may offer a dollar-for-dollar match (100% match up to 3% to 5% of salary) or tiered match structures (such as 100% on the first 3% plus 50% on the next 2%). Be aware that employer contributions may be subject to a vesting schedule, which specifies how long you must remain with the company before gaining full ownership of the matching dollars.
How We Calculate Your 401(k) Projection
Our retirement projection model applies deterministic annual compound interest accounting for dynamic contribution limits, salary increases, and investment fees. The basic conceptual equation governing each year's progress is:
Ending Balance = Starting Balance × (1 + Net Return) + Total Contributions × (1 + Net Return / 2)
Contribution Timing: Because employees contribute through recurring payroll deductions rather than a single lump sum on January 1, our calculation models ongoing contributions as earning approximately a half-year's return in the year they are deposited.
Net Investment Return: The net return rate equals your assumed gross annual return minus total plan administration and investment expense fees (Net Return = Expected Return − Fees).
Statutory Limits Enforcement: In every projection year, employee contributions are strictly evaluated against the age-based IRS elective deferral limit. If an employee turns 50 during the projection timeline, their individual limit automatically expands to include the $8,000 catch-up, and further adjusts to $11,250 during ages 60 to 63.
Today's Dollars vs. Nominal Dollars: Future balances are discounted using the standard inflation formula Balance / (1 + Inflation)^Years, allowing you to evaluate your future nest egg in terms of today's actual purchasing power.
401(k) Calculator Examples
To illustrate how starting early and increasing contributions transforms retirement outcomes, review these three realistic profiles calculated with our financial engine (assuming 7% return, 3% salary growth, 50% match up to 6%):
Example 1: Starting at Age 25
• Starting salary: $55,000
• Current balance: $5,000
• Contribution: 8% ($4,400/yr)
Example 2: Starting at Age 35
• Starting salary: $85,000
• Current balance: $45,000
• Contribution: 8% ($6,800/yr)
Example 3: Boosting from 6% to 10%
• Starting salary: $75,000
• Balance: $30,000
• Increased deferral: 10% vs. 6%