A Roth conversion moves pre-tax retirement money into a Roth account by paying income tax now in exchange for tax-free growth and withdrawals later.
Formula: tax due now = amount × marginal rate; Roth value = amount × (1 + growth)^years; traditional value = amount × (1 + growth)^years × (1 − retirement rate) + tax due now × (1 + growth)^years
Example: $50,000 converted at 24% costs $12,000 now and grows to $98,357.57 tax-free over 10 years at 7%.
Finance
Instant, private, and free
Roth Conversion Calculator.
Compare the tax due now on a Roth conversion with projected tax-free growth.
Set your values
Results update as you type.
Leave blank to assume the same rate in retirement.
Breakdown
FAQs
Is a Roth conversion worth it?
Converting tends to win when your tax rate today is lower than the rate you expect in retirement, because you pay the tax at the lower rate and all future growth is tax-free.
When do I pay tax on a Roth conversion?
You owe ordinary income tax on the converted amount in the year of the conversion. Paying that tax from outside the account lets the full balance keep growing in the Roth.
Does the calculator show a break-even point?
No. It compares the projected Roth balance with the after-tax traditional balance plus an invested side fund equal to the tax you would have paid now.
Cite this calculator
Canonical URL: https://mathify.one/en/finance/roth-conversion
Cite as: Mathify. (2026). Roth Conversion Calculator. https://mathify.one/en/finance/roth-conversion
Use Cases
Filling a low-income year
Convert while your marginal rate is temporarily low, such as between jobs or in early retirement.
Example: Converting $50,000 at a 24% rate costs $12,000 now and grows tax-free.
Comparing current and future rates
Test whether you expect to be in a higher bracket later, which favours converting now.
Example: At a 24% rate now and 32% later, the Roth advantage is about $7,869 over 10 years at 7%.
Legacy and tax diversification
Move money into a tax-free bucket to reduce required minimum distributions later.
Example: A smaller traditional balance means smaller future RMDs and less taxable income.
Frequently Asked Questions
- Is a Roth conversion worth it?
- Converting tends to win when your tax rate today is lower than the rate you expect in retirement, because you pay tax at the lower current rate and all future growth is tax-free.
- When do I pay tax on a Roth conversion?
- You owe ordinary income tax on the converted amount in the year of the conversion. Paying that tax from outside the account lets the full balance keep growing in the Roth.
- What does the projected traditional value include?
- It is the traditional balance after tax at your expected retirement rate plus an invested side fund equal to the tax you did not pay now, grown at the same rate.
- Can I undo a Roth conversion?
- Since 2018 conversions can no longer be recharacterized. Once you convert, the tax is owed for that year, so model the numbers first.
Tips & Common Mistakes
Tips
- Pay the conversion tax from a taxable account if you can, so the whole converted balance keeps growing.
- Convert only up to the top of your current tax bracket to avoid pushing other income into a higher rate.
- Watch for the IRMAA Medicare surcharge if you are within two years of enrolling.
- Consider spreading conversions over several years instead of one large event.
Common Mistakes to Avoid
- Paying the conversion tax out of the converted amount, which shrinks the balance that compounds.
- Ignoring state income tax on the conversion.
- Assuming a Roth always wins, even when the retirement rate is lower than the current rate.
- Forgetting that a conversion can raise the taxable portion of Social Security or other income.
Last updated: September 11, 2026