Compare contribution scenarios
Change monthly employee deferrals to see how contributions and modeled growth affect the ending balance.
Roth 401(k) Calculator
Enter your Roth balance, monthly contribution, years, and assumed return to get a projected balance and 2026 contribution-limit check.
Project a Roth 401(k) Balance
Enter your current Roth balance, monthly employee contribution, time horizon, assumed return, and 2026 age group.
Your projected balance, contributions, growth, and 2026 limit context will appear here.
How to Use Roth 401(k) Calculator
1
Enter Savings and Contributions
Use the Roth balance you want to model and your planned monthly employee contribution.
2
Set Time and Return
Choose the number of years and a return assumption you understand is not guaranteed.
3
Review Growth and Limit Context
Compare projected value, contributions, growth, and the selected 2026 employee limit.
Roth 401(k) Calculator Features
- Monthly compound-growth projection
- 2026 IRS elective-deferral context
- Contribution and growth breakdown
- Three 2026 age-limit groups
Common Use Cases
Check a 2026 contribution pace
Compare twelve months of entered contributions with the selected IRS elective-deferral limit.
Limits and Important Notes
Result type: Planning estimate
Calculation Details
- Compound the current balance monthly using the entered return.
- Add the employee contribution at each month end.
- Separate starting balance, new contributions, and modeled growth.
- Compare the annual contribution pace with the selected 2026 limit.
Formula
End-of-month future value with monthly contributions; annual contribution = monthly contribution × 12
Rounding
Calculations retain full precision; displayed currency rounds to whole dollars.
Default Assumptions
- The annual return remains constant and compounds monthly.
- Employee contributions are deposited at the end of each month.
- The entered contribution represents combined employee elective deferrals that count toward the selected limit.
- Employer contributions, fees, taxes, loans, withdrawals, inflation, and plan-specific rules are excluded.
Verified Example
Inputs: $10,000 current balance, $1,000 monthly, 25 years, 7% assumed return, under age 50.
Calculation: Compound $10,000 monthly for 300 months and add $1,000 after every month; annual employee deferral is $12,000.
Result: The page separates the projected balance into starting money, $300,000 of new contributions, and hypothetical growth.
Sources and Version
Version: 2026 elective-deferral limits
Applicable date: 2026
Last verified: 2026-08-14
Update responsibility: OnlineTool.me
- Internal Revenue Bulletin 2025-49 — Internal Revenue Service (accessed 2026-08-14)
- Retirement Topics — Designated Roth Account — Internal Revenue Service (accessed 2026-08-14)
- Returns are hypothetical and investment losses are possible.
- The 2026 limit check does not determine eligibility, compensation limits, plan terms, nondiscrimination rules, or tax treatment.
- Roth and pre-tax elective deferrals generally share the employee limit; confirm payroll and plan records.
- This is educational information, not tax, investment, legal, or retirement-plan advice.
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