Roth 401(k) Conversion Calculator
This calculator will show the advantage, if any, of converting your pre-tax 401(k) to a Roth 401(k).
How the roth 401(k) conversion calculator works
It treats an in-plan conversion of pre-tax 401(k) money to Roth: tax is paid now, then the balance grows tax-free. It compares that to leaving the money pre-tax and taxing it at withdrawal.
Worked example: with 401(k) amount to convert of $100,000, tax rate on the conversion of 24.00% and annual return of 7.00%, the roth 401(k) conversion calculator shows roth conversion advantage of $85,133.
- Conversion tax now
- $24,000
- Roth value (tax-free)
- $386,968
- If not converted (after tax)
- $301,835
- Net advantage
- $85,133
The formula
Roth value = amount × (1 + return)^years. Pre-tax after-tax = amount × (1 + return)^years × (1 − retirement tax rate). Conversion tax = amount × today’s rate.
Results are estimates for educational purposes and are not financial advice. Confirm exact figures with your lender, plan administrator or advisor.
Questions about the roth 401(k) conversion calculator
What is an in-plan Roth conversion?
Moving pre-tax money already in your 401(k) into the Roth side of the same plan. You pay income tax on the converted amount now, and it then grows and is withdrawn tax-free.
When should I do an in-plan conversion?
When you expect higher taxes later, can pay the tax from outside money, and want to build a tax-free bucket. A lower-income year is an ideal time to convert.
Does the conversion trigger a penalty?
The conversion itself is taxed but not penalized. However, converted amounts have their own 5-year clock for penalty-free withdrawal of earnings — confirm the rules before tapping it early.
Is the Roth 401(k) Conversion Calculator free to use?
Yes. Every calculator on FinCalculators is completely free, with no sign-up, login or paywall. You can run as many scenarios as you like.