Roth IRA Conversion Calculator

Enter your Traditional IRA balance, tax rates, and time horizon to compare converting to a Roth IRA against staying Traditional.

Roth IRA Conversion Calculator

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Traditional IRA balance to convert ($)

How will you pay the conversion tax?

Your current marginal tax rate (%)

Expected tax rate at withdrawal (%)

Expected annual growth (%)

Years until withdrawal

Tax due now on conversion	$24,000.00
Roth future value (tax-free)	$386,968.45
Traditional future value (after tax at withdrawal)	$294,096.02
Net benefit of converting	$92,872.43

Assumes a constant growth rate and tax rates. Excludes the pro-rata rule (if you hold other pre-tax IRA funds), state taxes, and IRMAA/Medicare premium effects. Not tax advice - consult a professional before converting.

The formula

Tax due now = Balance x Current marginal tax rate If paying from OUTSIDE funds: Roth invested = full Balance If withheld FROM the conversion: Roth invested = Balance - Tax due now Roth future value = Roth invested x (1 + growth)^years (tax-free) Traditional future value = Balance x (1 + growth)^years x (1 - future tax rate)

Example

$100,000 converted, 24% tax now, 24% expected tax at withdrawal, 7% growth over 20 years, tax paid from outside funds: $24,000 due now, Roth grows to $386,968.45 tax-free versus $294,096.02 for staying Traditional - a net benefit of $92,872.43 for converting, purely from paying the tax with outside money.

Step-by-step guide

Enter the Traditional IRA balance you're considering converting - this can be a partial or full conversion of your account.
Choose how you'll pay the conversion tax - paying from outside funds keeps 100% of the balance growing tax-free in the Roth; withholding from the conversion itself means less money converts.
Compare your current tax rate to your expected future rate - this comparison, more than any other single factor, determines whether converting makes sense.

Why HOW you pay the conversion tax changes the math entirely

This is the single most overlooked detail in Roth conversion planning. If your current and future tax rates are identical, and you pay the conversion tax by withholding it from the IRA itself, converting to Roth versus staying Traditional produces mathematically IDENTICAL results - there's no inherent advantage either way. But if you pay that tax bill from money OUTSIDE the IRA (savings, a taxable brokerage account), the FULL original balance converts and grows tax-free, while the Traditional alternative still has that same balance taxed away at withdrawal. This turns an otherwise-neutral decision into a genuine advantage for converting, effectively because you're finding a way to get more money into tax-advantaged growth than you started with.

Common mistakes

Withholding the conversion tax from the IRA itself when under age 59½ - this can trigger a 10% early withdrawal penalty on the withheld amount, on top of losing that portion's tax-free growth potential.

Ignoring the pro-rata rule when you hold other pre-tax and after-tax IRA money across multiple accounts - the IRS treats all your traditional, SEP, and SIMPLE IRAs as one combined pool for conversion tax purposes, which can produce a different taxable amount than converting a single account in isolation would suggest.

Frequently asked questions

Can I undo a Roth conversion if I change my mind?

No - Roth conversions are irreversible under current tax law. This makes it especially important to model the tax impact carefully before converting, since there's no way to reverse the decision afterward.

Is there a waiting period before I can withdraw converted funds tax-free?

Yes - each conversion has its own separate 5-year clock. Withdrawing converted funds before that specific conversion's 5-year period ends can trigger a 10% penalty, even though you already paid income tax on the conversion itself.

Why would someone convert even if their current and future tax rates are the same?

Beyond the outside-funds tax-payment advantage, Roth IRAs aren't subject to Required Minimum Distributions during the original owner's lifetime, offering more flexibility in retirement and potential estate-planning benefits that a Traditional IRA doesn't provide.

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