401(k) Calculator: Contributions, Match, and Growth
Estimate how employee contributions, employer matching, salary growth, and investment returns may affect a 401(k) balance.
Inputs and calculation method
- Current 401(k) balance
- Salary and employee contribution rate
- Employer match formula and limit
- Return, fees, raises, and years until retirement
The calculator estimates employee and employer deposits for each period, applies the selected growth assumption, and repeats through the selected retirement date.
Core formula: Annual additions ≈ employee contribution + eligible employer match; projected value compounds each addition for its remaining investment period.
How to interpret the estimate
Contributing enough to receive the full available employer match can materially increase total deposits, subject to plan terms and vesting.
Change one assumption at a time to understand which input has the greatest effect. Use exact figures from a lender disclosure, statement, pay record, account terms, or business records whenever possible. Calculator output is rounded and may differ from institution-specific calculations.
How to use this calculator effectively
Use the employer plan document and current official rules to verify match, vesting, contribution, and tax assumptions.
Use the 401(k) calculator with the employer’s plan document, contribution election, match formula, vesting schedule, investment fees, and pay frequency. Separate employee contributions from employer money so the result shows which assumptions depend on plan rules. Do not hard-code an annual legal limit without checking the applicable year and personal eligibility.
- Step 1: Current 401(k) balance. Use a value from a current statement, written quote, account record, or documented plan whenever possible.
- Step 2: Salary and employee contribution rate. Use a value from a current statement, written quote, account record, or documented plan whenever possible.
- Step 3: Employer match formula and limit. Use a value from a current statement, written quote, account record, or documented plan whenever possible.
- Step 4: Return, fees, raises, and years until retirement. Use a value from a current statement, written quote, account record, or documented plan whenever possible.
What changes the result most
- Employee contribution rate: deposits from each paycheck form the most direct controllable input.
- Employer match: formulas, compensation definitions, true-up provisions, and annual limits determine the amount actually contributed.
- Vesting: unvested employer money may be forfeited after leaving the employer.
- Return and fees: investment selection and plan expenses influence long-term growth, but future performance is uncertain.
Practical decision guide
Confirm the match formula and contribute enough to capture the available match when that fits the broader budget. Model salary growth and contribution increases separately rather than assuming both occur automatically. Compare traditional and Roth contributions with qualified tax guidance when the choice is material; the calculator’s projected balance alone cannot identify the better tax treatment.
Questions to ask before relying on the result
- Which input is documented and which one is only an assumption?
- How does the result change under a more conservative rate, cost, payment, or time horizon?
- What cash-flow, risk, tax, legal, or contractual factor is not represented by the formula?
Common mistakes to avoid
- Entering the maximum advertised match without applying the plan’s formula or compensation cap.
- Counting unvested employer contributions as guaranteed assets.
- Using contribution limits from a previous year.
- Comparing traditional and Roth balances without considering current and future taxes.
Limitations and how to verify the estimate
Plan provisions, legal limits, taxes, investment options, fees, loans, withdrawals, vesting, and employer contributions vary. The summary plan description and current IRS guidance control over this estimate.
Recheck the calculation when an input changes and compare the output with the applicable statement, disclosure, contract, plan document, or official source. Do not use a calculator result as a substitute for individualized financial, tax, legal, lending, investment, insurance, payroll, or accounting advice.
Save the date, inputs, and purpose of each scenario. That record makes later comparisons more reliable and helps explain why a result changed. When comparing alternatives, use the same measurement period and cost definitions; otherwise a seemingly better result may come from inconsistent assumptions rather than a genuine financial advantage.
Official references and further reading
- Internal Revenue Service: 401(k) plans — Official information about 401(k) plan rules and plan types.
- Investor.gov: Saving and investing — Investor education about long-term saving assumptions and risk.
Frequently asked questions
How does employer matching work?
Plans use different formulas, limits, eligibility rules, and vesting schedules. Use the summary plan description.
Are contribution limits included?
Limits can change by year and age. Confirm current IRS and plan limits rather than relying solely on a calculator default.
Does the result show after-tax spending money?
Usually not. Traditional and Roth contributions have different tax treatment, and future withdrawals may be taxable.
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Last technical review: June 26, 2026. Methodology is provided for transparency. This calculator is educational and does not provide financial, tax, legal, investment, lending, insurance, or accounting advice. Read the methodology and calculator disclaimer.