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Roth conversion calculators

Everything runs in your browser — no account, no upload, and nothing you type is transmitted. Save a scenario to this browser, or share it as a link that carries your figures in the URL fragment.

What the conversion ladder calculator computes

The live tool models a multi-year ladder rather than pricing a single conversion, which is the distinction that matters: the plan usually fails on cash flow or on a forfeited subsidy, not on the bracket everyone optimizes.

  • Every five-year seasoning clock

    One bar per conversion, with a marker for today — amber while a rung is seasoning, emerald the year it becomes liquid.

  • The true marginal rate, not the bracket

    Federal tax plus any forfeited ACA premium tax credit, divided by the amount converted. Frequently well above the bracket you were aiming at.

  • Proximity to the 400% FPL cliff

    How many more dollars you can convert before the entire premium tax credit is forfeited, and what that increment would cost.

  • Bridge-fund solvency

    Whether your taxable savings actually cover living expenses plus conversion tax through the five-year wait, and the year they run dry if not.

  • Pro-rata basis recovery

    After-tax basis is recovered proportionally across conversions, so the taxable portion of each rung reflects Form 8606 arithmetic.

  • Shareable, portable scenarios

    Inputs are encoded in the URL fragment, which never reaches a server. Save scenarios locally, or download the results as an Excel workbook.

What it deliberately does not model

Named here rather than left for you to discover. Each of these can change a conversion decision, and each has a guide explaining where it bites.

  • State income tax

    Rules vary too much across states to model responsibly. Read the output as a floor and add your own rate.

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  • Medicare IRMAA surcharges

    A two-year lookback means conversions from age 63 raise premiums at 65. Outside the window for most early retirees, and priced by a separate calculator.

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  • The 0% capital gains interaction

    Conversion income can push long-term gains out of the 0% bracket. Not modeled as a combined optimization.

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  • Multi-account IRA aggregation

    Enter your combined Traditional, SEP, and SIMPLE IRA total — the tool does not aggregate accounts for you.

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How the tools are built

Every figure is computed in your browser from the 2026 federal brackets and the published ACA applicable-percentage schedule. The tables on the methodology page are generated from the same configuration the engine calculates with, so the documentation cannot drift from the math — if a figure there is wrong, the calculator is wrong the same way.

There is no server component. Your inputs live in the page and, if you share a scenario, in the URL fragment after the # — which browsers never transmit in a request. Saved scenarios stay in your own browser storage. The privacy policy covers both, along with the third-party services the site loads (Google Analytics and Google AdSense).

Start with the concepts

A calculator is more useful once you know which constraint you are up against. These cover the mechanics and the four costs that routinely exceed the tax saving.

Or see all guides, including three worked exampleswith every figure computed.