How much should I convert to a Roth?

A common strategy is to convert up to the top of your current bracket — the "room left" figure. Converting beyond it pushes the extra dollars into a higher rate.

Roth Conversion Calculator (2026) — Fill Your Tax Bracket

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Roth Conversion

Conversion tax • Bracket room

Filing status

Current taxable income ⓘ

Amount to convert

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Enter your income and conversion amount

How the Roth Conversion Calculator Works

Enter your current taxable income and how much you want to convert.
We add the conversion to your income and compute the extra federal tax using 2026 brackets.
See your effective rate, the bracket you reach, and how much room is left before the next bracket.

The "Fill the Bracket" Roth Strategy

A Roth conversion moves money from a traditional IRA/401(k) to a Roth — you pay income tax now so withdrawals are tax-free later. The smart move is to convert just enough to "fill" your current tax bracket without spilling into the next one. This calculator shows the tax cost, your effective rate on the converted amount, and your remaining room to the next bracket so you can size the conversion precisely.

Conversions also raise MAGI, which can affect Medicare IRMAA two years later and the taxation of Social Security — worth modeling alongside this. Estimate only; not tax advice.

Formula & Logic

A Roth conversion moves money from a tax-deferred account to a Roth, paying tax now to avoid tax later. The decision rests on the same rate comparison as the Roth-versus-traditional choice, but with two additional considerations that often dominate. The conversion is added to ordinary income, so a large one can push you into a higher bracket, trigger IRMAA Medicare surcharges two years later, or increase the taxable share of Social Security. And paying the tax from outside the account rather than from the converted balance is what makes conversions genuinely valuable — it effectively shelters extra money.

Tax on conversion = Converted amount × marginal rate (may span brackets)Future Roth value = Converted × (1 + r)^n, tax-freeFuture traditional value = Converted × (1 + r)^n × (1 − future rate)Convert up to the top of your current bracket, not beyond

where:

bracket room: the amount you can convert before crossing into the next rate
IRMAA: Medicare surcharge triggered by income two years earlier
tax source: paying from outside funds shelters more than paying from the conversion

Assumptions: No recharacterisation since 2018 — a conversion is irreversible. The five-year rule applies separately to each conversion for penalty-free access to converted principal before 59½.

SourceIRS: Roth IRAs

Step-by-Step Example: Converting $80,000 in a Low-Income Year

An early retiree converts before Social Security and RMDs begin.

Conversion$80,000
Current rate22%
Expected rate at 7524%
Growth20 years at 7%

Tax due now: $80,000 × 22% = $17,600, paid from taxable savings.
Grow the converted balance: $80,000 × 1.07²⁰ = $309,575, entirely tax-free.
Left in the traditional IRA instead, the same $80,000 also grows to $309,575.
But withdrawal at 24% costs $74,298, leaving $235,277.
Advantage of converting: $309,575 − $235,277 = $74,298.
Less the $17,600 tax paid: a net gain of $56,698 in future dollars.

ResultConverting gains about $74,298 of future tax-free value

The window between retirement and age 73 — after employment income stops but before Social Security and RMDs start — is when marginal rates are lowest and conversions are most valuable. Converting only up to the top of the 22% bracket each year, repeatedly, usually beats one large conversion that spills into 32%.

Roth Conversion FAQ

How much should I convert? ▾

A common strategy is to convert up to the top of your current bracket — the "room left" figure here. Converting beyond it pushes the extra dollars into a higher rate.

When is a Roth conversion worth it? ▾

Generally when your current tax rate is lower than your expected rate in retirement — for example in a low-income gap year before RMDs and Social Security begin.

Does a conversion affect Medicare or Social Security? ▾

Yes — it raises MAGI, which can trigger higher Medicare IRMAA premiums two years later and increase the taxable portion of Social Security. Model those too.

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