401(k) Retirement Income Calculator

Worked example

A $1,000,000 balance at 4% → $40,000/year or about $3,333/month initial income under the stated assumption.

When to use this

• Translating a projected nest egg into a rough monthly income figure.
• Testing alternative withdrawal rates such as 3.5% or 4.5%.
• Discussing income assumptions with a planner using transparent inputs.

Common mistakes

• Treating the 4% rule as a guarantee.
• Forgetting taxes on Traditional withdrawals.
• Ignoring other income sources like Social Security.

How it works

Estimates initial annual and monthly retirement income from a 401(k) balance using a withdrawal-rate assumption (commonly 4%). Optionally illustrates how many years a constant real withdrawal might last under a simple return/inflation path. Not a guarantee of sustainable spending.

Limitations

Results are estimates for educational purposes and are not financial advice. Withdrawal rates are planning assumptions, not guarantees of sustainable spending.

Privacy and file handling

Your data stays on your device and is not uploaded.

Accuracy & methodology

This section documents how the calculator works, what it leaves out, and when results were last reviewed. Figures are educational estimates—not professional advice—and are not labeled "current" unless tied to automatically updated reference data.

Formula source or methodology

annualIncome = balance × withdrawalRate%; monthly = annual/12; optional depletion sketch with real return.

Jurisdiction

United States (educational)

Unit system

US dollars and percents

Rounding method

Currency amounts round to two decimal places (half up via Math.round × 100 / 100).

Assumptions

• Labeled withdrawal rate (often 4%) is a planning heuristic
• Constant real withdrawal in the sustainability sketch

Known omissions

• Not tax, legal, investment, or lending advice. Confirm material decisions with qualified professionals.
• 2026 IRS contribution limits ($24,500 elective deferral; $8,000 catch-up age 50+; $11,250 catch-up age 60–63; $72,000 combined annual additions under §415(c), subject to applicable rules) — confirm plan documents; some tools enforce elective-deferral and §415(c) caps while others are estimate-only
• Employer match annual caps, true-up provisions, and vesting schedules
• Plan administrative fees and fund expense ratios unless a fee field is provided
• Inflation adjustment of future dollars (nominal dollars only unless stated)
• Income tax on withdrawals (pre-tax vs Roth treatment)
• Required minimum distributions (RMDs) and early withdrawal penalties

Test cases (automated)

• $1M at 4% → $40,000/year and ~$3,333/month

Version & last verified

Logic version 1.0. Content and formulas last verified 2026-09-12.