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A Roth conversion calculator estimates how converting traditional retirement savings to a Roth account could affect taxes and future retirement outcomes. There is no single best tool for every household: use a focused calculator to estimate the tax effect of a proposed conversion, or a broader planner when you need to model several years alongside required minimum distributions (RMDs), Social Security, Medicare premiums, or health-insurance subsidies. These are scenario estimators, not guarantees of tax savings or personalized recommendations.
At a glance
| Name | Best for | Key spec | Checked |
|---|---|---|---|
| Vanguard Roth Conversion Calculator | Comparing current and future tax assumptions | Models growth, RMD effects, potential IRMAA surcharges, and a break-even tax rate | November 2026 |
| Schwab IRA Roth Conversion Calculator | Estimating the tax effect of a selected conversion amount | Inputs include taxable income, filing status, conversion amount, federal tax, optional state tax, and tax paid outside the IRA | November 2026 |
| Fidelity Roth Conversion Calculator / Evaluator | Estimating current taxes across different conversion amounts | Methodology describes current federal and state taxes, sensitivity analysis, and an estimated cumulative after-tax benefit or loss | November 2026 |
| RothHelper Roth Conversion Optimizer | Exploring year-by-year conversion strategies | Vendor describes modeling RMDs, Social Security, IRMAA, ACA subsidy cliffs, state tax, and other factors; page displayed version 6.24.3 | November 2026 |
| MOAA Roth IRA Conversion with Distributions Calculator | Comparing retirement net worth and future RMD effects | Estimates net-worth change at retirement and compares RMD effects for the owner and beneficiaries | November 2026 |
This comparison is U.S.-focused. Feature descriptions are attributed to the calculator publishers; they are not independent validations of the tools’ calculations.
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Which Roth conversion calculator should I use?
Choose based on what you need to model, not on a single projected savings figure. A one-time tax estimate and a multi-year retirement plan answer different questions.
- For a current-versus-future tax-rate comparison: Start with Vanguard. Its calculator describes a break-even tax-rate view and includes growth, RMD effects, and potential IRMAA surcharges in its modeled factors.
- For a selected conversion amount and its estimated tax impact: Schwab’s calculator accepts information such as taxable income, filing status, conversion amount, and optional state tax. It also lets the user model paying the tax with funds outside the IRA.
- For comparing several conversion amounts and assumptions: Fidelity’s calculator and evaluator focus on current tax estimates and sensitivity analysis. Fidelity says the methodology is intended for relatively simple financial situations and relies on assumptions.
- For year-by-year planning across retirement factors: RothHelper describes an optimizer that models multiple conversion strategies alongside RMDs, Social Security, IRMAA, ACA subsidy cliffs, and state tax. Confirm that its current version addresses the specific factors you need.
- For another view of net worth and distributions: MOAA describes a calculator for estimating changes in retirement net worth and comparing future RMD effects for the account owner and beneficiaries.
These are different scopes, not interchangeable measures of accuracy. If a calculator omits an important factor in your situation, a precise-looking output does not make that factor irrelevant.
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What does a Roth conversion calculator estimate?
It estimates how converting some traditional retirement savings to a Roth account could affect taxes now and, depending on the tool, modeled taxes or account outcomes later. The conversion amount can increase taxable income in the year it happens, so the estimate depends on the amount, existing taxable income, filing status, and applicable tax rates.
Tools differ in how far they project. A short-form calculator may emphasize the current tax cost and a comparison under future tax-rate assumptions. A broader planner may also describe modeling year-by-year conversions and interactions with RMDs, Social Security, Medicare income-related monthly adjustment amounts (IRMAA), or ACA health-insurance subsidies. Check the input list and assumptions rather than assuming a tool covers every retirement consequence.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchA calculator’s result is conditional: it reflects the information and assumptions entered. The apparent advantage can change with future tax rates, investment growth, withdrawals, conversion timing, and how the tax bill is paid. Comparing more than one conversion amount and more than one future-tax assumption is more informative than treating one output as a yes-or-no verdict.
How should I use a calculator to estimate taxes on a Roth conversion?
Gather your financial inputs first, then compare scenarios rather than relying on a single estimate. The exact fields vary by calculator, and an estimate is only as useful as its assumptions.
- Choose the question you want answered. Decide whether you are estimating the tax cost of one conversion, comparing current and future tax assumptions, or planning conversions over multiple years. Pick a tool whose described scope matches that question.
- Collect the inputs the tool requests. These may include the proposed conversion amount, taxable income, filing status, state-tax information, and assumptions about future tax rates and investment growth. Use figures that reflect your circumstances; do not substitute a different filing status or state just to get a favorable result.
- Check how it treats the conversion tax. Schwab’s assumptions model paying the tax with funds outside the IRA. Schwab cautions that using IRA funds to pay the tax can diminish the potential benefit. Make sure the calculator’s assumption matches the scenario you are evaluating.
- Run several conversion amounts. Compare a range of plausible amounts so you can see how the estimated tax effect changes. A result for one amount does not establish that amount as optimal.
- Vary future assumptions. Test different future tax-rate and growth assumptions where the calculator allows it. If the tool models retirement factors such as RMDs, IRMAA, or subsidies, confirm which ones are included and how the output describes them.
- Review exclusions and the date of the tax assumptions. Look for notes about omitted taxes or factors and check whether tax tables are current for the year you are planning. A tool’s page or methodology may explain limitations that are not visible in its headline result.
- Take the scenarios to a qualified tax or financial professional when the decision is material or complicated. Share the assumptions and inputs as well as the output. A calculator cannot know your full tax circumstances or guarantee the result.
What can make the estimate misleading?
The most common problem is reading a hypothetical output as a forecast or recommendation. A calculator cannot know future tax law, future investment returns, or every detail of a household’s tax situation.
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Assuming the tax bill is paid from the wrong source
The source of the conversion-tax payment matters to the modeled comparison. Schwab assumes that tax is paid with funds outside the IRA and says paying it from IRA funds can diminish the potential benefit. If your actual plan differs from the calculator’s assumption, treat its projected comparison accordingly.
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Schwab offers an optional state-tax input, but also warns that states can treat conversion income differently. Its assumptions say the tool does not model the alternative minimum tax (AMT). A federal estimate alone—or a state estimate based on an unsuitable assumption—may not capture your total tax effect.
Using stale tax tables or treating future rates as certain
Tax tables and future-rate assumptions can affect results. Fidelity’s methodology says its evaluator may lag tax-table updates; Schwab’s cited calculator page includes 2025 bracket values, which should not be treated as current 2026 rates without a current-year source. A future tax-rate assumption is a scenario input, not a prediction that the law will remain unchanged.
Asking a simple calculator to answer a multi-year planning question
A single-year estimate may not show how conversions could interact over several years with RMDs, Social Security, IRMAA, ACA subsidies, or other household income. If those effects matter, check whether the chosen tool explicitly models them. A broader tool’s feature list is still a description from its publisher, not proof that every personal circumstance is covered.
How do the calculators differ in detail?
The key distinction is how much of the decision each tool is designed to represent. The descriptions below summarize the publishers’ stated capabilities and caveats.
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Vanguard: a break-even tax-rate comparison
Vanguard’s Roth Conversion Calculator is suited to comparing current and future tax assumptions. The publisher says it considers current and future tax brackets, growth, RMD effects, potential IRMAA surcharges, and a break-even tax rate. That makes it a useful fit when the central question is how modeled future tax rates compare with the current tax cost. Vanguard says the tool is not tax or legal advice; check the assumptions and inputs and do not treat its result as a recommendation.
Schwab: a selected amount and estimated tax effect
Schwab’s IRA Roth Conversion Calculator focuses on estimating the tax effect of a conversion amount. Its described inputs include taxable income, filing status, conversion amount, federal tax, optional state tax, future tax rate, investment growth, and whether tax is paid outside the IRA. Schwab describes it as educational rather than investment advice and says its results are hypothetical. Its assumptions exclude AMT and note that state treatment can differ. Because the page includes 2025 federal bracket figures, do not reuse those figures as current 2026 rates without checking a current-year source.
Fidelity: current taxes and sensitivity analysis
Fidelity’s Roth Conversion Calculator / Evaluator estimates current taxes for different conversion amounts. Fidelity’s methodology describes a rough estimate of cumulative after-tax benefit or loss, current federal and state taxes, and sensitivity analysis. The methodology says it relies on assumptions, is intended for relatively simple financial situations, and may lag tax-table updates. Fidelity also cautions that the calculator is not a guarantee or individualized tax advice.
RothHelper: vendor-described multi-year planning
RothHelper’s Roth Conversion Optimizer is intended for readers exploring multiple conversion strategies over time. The vendor says it models RMDs, Social Security, IRMAA, ACA subsidy cliffs, state tax, and other retirement factors. The page displayed version 6.24.3 and a November 2026 update. Those are vendor-described capabilities, not independently tested claims; confirm the current version, its assumptions, and whether the features cover your specific situation.
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MOAA: net-worth and distribution effects
MOAA’s Roth IRA Conversion with Distributions Calculator is a secondary option if you want to compare estimated total net worth at retirement and future RMD effects for the owner and beneficiaries. The page describes those intended calculations, but does not provide independent validation of the results.
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How to compare the outputs side by side
When two tools show different results, first check whether they are calculating the same thing. One may emphasize the tax attributable to a single conversion, while another estimates cumulative after-tax outcomes or retirement net worth over time. A difference is not automatically an error if the time horizon, included factors, or assumptions differ.
Use a short checklist for each output:
- Time horizon: Is this a one-time comparison or a projection across several years?
- Tax inputs: Are federal and state taxes included, and does the state assumption match your circumstances?
- Payment source: Does the model assume conversion taxes are paid from outside the IRA?
- Future scenario: Which future tax rate, growth, withdrawal, and timing assumptions drive the result?
- Retirement interactions: Does the tool say it includes RMDs, Social Security, IRMAA, ACA subsidy effects, or other income?
- Recency and exclusions: Are tax tables dated, and are omitted factors clearly identified?
Write down the inputs beside the output so that a later comparison remains meaningful. If a tool does not disclose an assumption you need, do not silently treat the missing factor as zero or assume another calculator handles it the same way. A more detailed-looking estimate is not necessarily a better fit if its scope is opaque.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How we picked these options
The shortlist reflects the calculator types and capabilities described in the reviewed sources: a break-even tax-rate comparison, a selected-amount tax estimate, current-tax sensitivity analysis, year-by-year strategy modeling, and net-worth or RMD comparisons. The comparison also considers whether publishers describe federal and state tax inputs, how conversion taxes are assumed to be paid, and whether they disclose limitations. No calculator was independently tested, and no user-specific tax outcome was calculated.
When should I get professional advice?
Get individualized advice when the conversion could materially affect your taxes or when several tax and retirement factors interact. A tool’s result is an estimate, and both Schwab and Fidelity encourage readers to consider professional advice when appropriate.
Bring the proposed conversion amounts, the calculator’s assumptions, and any relevant outputs to the discussion. Ask whether the estimate reflects your filing status, taxable income, state treatment, expected source of tax payment, and the retirement factors the calculator may omit. This helps a professional evaluate the scenario rather than treating one calculator result as a final answer.
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Fidelity states that a Roth conversion cannot be reversed. That makes it especially important to review the full tax circumstances and assumptions before acting, rather than relying on a single modeled outcome.
Frequently Asked Questions
Are these Roth conversion calculators meant for people outside the United States?
The tools compared here are U.S.-focused, using U.S. retirement-tax assumptions and features such as federal tax, state tax, IRMAA, or ACA subsidies. Someone filing under another country’s tax system should not assume the estimates apply.
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Does a calculator tell me the exact amount I should convert?
No. It estimates outcomes from the inputs and assumptions selected; it does not establish an optimal amount for your household or guarantee savings. Treat its output as a scenario to review, not an instruction to convert.
What should I do if two calculators give different results?
Compare their inputs, tax-rate assumptions, tax-payment assumptions, and modeled factors before comparing the final figures. Different tools may answer different questions, so a mismatch can reflect scope or assumptions rather than a simple calculation error.
Is there a formula or calculator for finding the optimal Roth conversion?
There is no single calculator in this comparison that can establish an optimal amount for every household. Use tools to compare plausible conversion amounts and assumptions, then account for factors they may omit. A reader discussion on r/Bogleheads raises this same kind of question, but it does not establish a universal formula or an optimal answer.
Can I reverse a Roth conversion if the estimate turns out to be wrong?
Fidelity says a Roth conversion cannot be reversed. Because the decision is not reversible, review the assumptions, tax-payment plan, and your full circumstances before acting; do not treat a calculator’s output as a guarantee.
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Bottom line: Choose a Roth conversion calculator by the question it can answer: a single-conversion tax estimate, a current-versus-future break-even comparison, or a broader multi-year retirement scenario. Compare several conversion amounts and assumptions, verify state and tax-payment inputs, and check the tool’s exclusions and tax-table date. Treat every result as an estimate—not a recommendation—and get professional advice when the decision or its interactions are material.
