Roth Conversion Calculator
Pay tax now, or pay it later? Find the break-even point
A Roth conversion moves pre-tax retirement money into a Roth IRA and triggers income tax on the converted amount today, in exchange for tax-free growth and withdrawals. Converting wins when your tax rate now is lower than the rate you expect in retirement — or when you can pay the tax from outside funds.
The Math Behind the Roth Conversion Calculation
| Variable | Meaning |
|---|---|
| C | Amount converted |
| g | Annual growth rate |
| y | Years until withdrawal |
| t_now | Marginal tax rate on the conversion |
| t_ret | Expected tax rate in retirement |
Worked Example
Convert $50,000 at 24%, grow 7% for 20 years, retirement rate 22%: tax today $12,000; Roth grows to $193,484 tax-free. Keeping it traditional leaves $193,484 × 0.78 = $150,918 after tax. Paying the $12,000 from a taxable account costs about $41,000 in forgone growth, so the gap narrows — run the numbers with your own rates.
💡 Pro Tip: Convert in low-income years and mind the bracket edges
The best conversion windows are early retirement before Social Security/RMDs, a sabbatical year, or a business-loss year. Fill your current bracket without spilling into the next one, and remember conversions can raise Medicare IRMAA premiums and reduce ACA subsidies two years later.
Roth Conversion Calculator
Inputs
Results
| Year | Keep Trad. | Convert |
|---|---|---|
| 0 | $39,000 | $38,000 |
| 1 | $41,730 | $40,786 |
| 2 | $44,651 | $43,767 |
| 3 | $47,777 | $46,957 |
| 4 | $51,121 | $50,370 |
| 5 | $54,700 | $54,022 |
| 6 | $58,528 | $57,929 |
| 7 | $62,625 | $62,110 |
| 8 | $67,009 | $66,584 |
| 9 | $71,700 | $71,371 |
| 10 | $76,719 | $76,493 |
| 11 | $82,089 | $81,973 |
| 12 | $87,835 | $87,837 |
| 13 | $93,984 | $94,112 |
| 14 | $100,563 | $100,826 |
| 15 | $107,602 | $108,009 |
| 16 | $115,134 | $115,696 |
| 17 | $123,194 | $123,921 |
| 18 | $131,817 | $132,721 |
| 19 | $141,045 | $142,138 |
| 20 | $150,918 | $152,213 |
Based on your results — what to do next:
Project your full Roth IRA
Your $50,000 conversion becomes $193,484 tax-free in 20 years — add regular contributions to see the whole picture.
See how conversions shrink future RMDs
Moving $50,000 out of your traditional balance reduces the account forced into taxable distributions at 73.
Fit it into your retirement plan
Converting adds about $1,296 of after-tax value — check your overall retirement number.
Roth Conversion Calculator FAQ
When does a Roth conversion make sense?
When your marginal tax rate today is at or below your expected retirement rate, when you have decades of growth ahead, and when you can pay the conversion tax from non-retirement funds.
How is a Roth conversion taxed?
The converted amount is added to your ordinary income for the year and taxed at your marginal rate. There is no 10% penalty on conversions, though converted funds have a 5-year clock before penalty-free early withdrawal of principal.
Should I pay the tax from the converted money?
Paying from outside funds preserves more in the Roth and is generally better. Paying from the converted amount shrinks the Roth and, if you are under 59½, may trigger a 10% penalty on the withheld portion.
Can I undo a Roth conversion?
No. Since the 2017 tax law, recharacterizations of conversions are not allowed, so plan the amount carefully — and consider converting in stages.
Does converting reduce required minimum distributions?
Yes. Roth IRAs have no lifetime RMDs, and a smaller traditional balance means smaller RMDs from age 73, which can lower future taxes and Medicare premiums.