Roth vs Traditional 401(k) Calculator United States 2026
Roth and traditional employee elective deferrals share one 2026 cap: $24,500 (IRS). This tool compares the same gross dollars after federal income tax, not two different paycheck costs.
Traditional FV after tax = C × (1 + r)^n × (1 − retirement rate)
Roth FV = C × (1 − current rate) × (1 + r)^n
If the two rates are equal, the future values match. Roth wins if you expect a higher rate later; traditional wins if you expect a lower rate later.
Worked example
$24,500 at 22% now and 22% later, 20 years, 7% return: tie.
$24,500 at 22% now and 32% later: Roth keeps more after tax.
Worked rate bets: Roth vs traditional $10,000 at 22% / 12%. Leftover 24% now / 12% later: traditional $34,053.22 vs Roth $29,409.60.
| Current rate | Retirement rate | Winner |
|---|---|---|
| 22% | 22% | Tie |
| 22% | 32% | Roth |
| 32% | 22% | Traditional |
What this does not include
- Catch-up ($8,000 / $11,250)
- Employer match
- State tax, NIIT, RMDs
- FICA (both types still pay Social Security and Medicare)
Related: 401(k) deferral limit, paycheck take-home, IRA contribution.
Educational estimate. Confirm with your plan or a tax professional.
Official sources
Yes. Combined employee elective deferrals. Catch-up is not in this version.
Yes. Only federal income tax treatment differs.
No. No state tax, NIIT, RMDs, or employer match.