Mega Backdoor Roth Calculator
The mega backdoor Roth lets you move up to the 2026 total 401(k) cap of $72,000 into Roth — far beyond the $24,500 pre-tax limit. Enter your salary and current contributions to see your after-tax room.
How to use this calculator
- Enter annual salary.
- Enter your pre-tax 401(k) contributions this year.
- Your results appear instantly below and update as you change the numbers.
How this calculator works
For 2026 the combined employee-plus-employer limit is $72,000 ($80,000 with catch-up). Pre-tax and Roth employee contributions share the $24,500 limit; after-tax contributions can go above it, up to the combined cap minus what you and your employer already put in. Converting those after-tax dollars to Roth — either in-plan or at rollover — is the mega backdoor Roth, and because the after-tax money was contributed post-tax, only the growth is taxable.
Frequently asked questions
Is the mega backdoor Roth allowed at every company?
No. Your plan must allow after-tax contributions and either in-plan Roth conversions or a rollover of after-tax money to a Roth IRA. Fewer than half of 401(k) plans offer it — check your plan document or ask your benefits team.
How is this different from a regular backdoor Roth IRA?
A backdoor Roth IRA works around the Roth IRA income limit using a traditional IRA. The mega backdoor Roth is separate: it uses after-tax 401(k) contributions, which have no income limit, and lets you get far more money into Roth each year.
Disclaimer: Results are estimates for general information only and do not constitute financial, tax, or legal advice. Figures reflect 2026 rules and may change. Always confirm current limits and consult a qualified professional before making decisions. Official figures: IRS.gov · 2026 limits per IRS tax inflation adjustments.