401(k) Contribution Limit Calculator 2026: methodology
Formulas, constants, and sources used for this calculator.
What this page is
This methodology page explains the formulas, constants, and assumptions used in this calculator.
We publish these details so you can verify how numbers are produced.
Calculator constants (values used)
| Constant | Value used | Notes |
|---|---|---|
| Employee deferral limit | $24,500 | 2026 estimate (update when IRS publishes official limits) |
| Catch-up (50+) | $8,000 | Used when age ≥ 50 |
How the calculation works
We calculate the maximum employee contribution based on age.
We then subtract your year-to-date contributions to estimate remaining room.
Finally, we divide the remaining amount by the number of paychecks left to estimate a per-paycheck target.
Rounding and formatting
We round to the nearest cent for dollar amounts.
This tool is designed for planning and education, not as a substitute for official IRS worksheets.
Sources
- IRS (irs.gov) annual inflation adjustment releases
- IRS publications and instructions (Form instructions)
- SSA.gov for Social Security related thresholds (when applicable)
Note: some 2026 values are placeholders until the IRS publishes the final numbers. We update this page when official releases go live.