Roth Conversion Calculator & Drawdown Optimizer
A free tool that plans your whole retirement cash flow: it funds your living expenses, pays the tax on your income and conversions from the right account, and finds the conversion schedule that leaves you the most after-tax wealth. It works as a Roth IRA conversion calculator for a traditional IRA or 401(k): you see the tax on every conversion, year by year, not just this year's.
Result
What this plan is doing
Year-by-year plan
| Age | IRA | Roth | Taxable | RMD | Convert | Extra IRA draw | Roth draw | Taxable sold | Spending | Taxable inc | MAGI | Top rate | Medicare | Tax |
|---|
Reading the tax columns: Tax is the whole income-tax bill for the year — federal, state, the 3.8% investment surtax and any early-withdrawal penalty, all in one number. Medicare is separate and additional: it is a premium surcharge, not a tax, so it is never inside the Tax column. Add the two to get the cash the plan hands over that year.
Not tax or investment advice. I'm not a CPA, enrolled agent or financial advisor. This tool models your living expenses and draws them — plus the tax on your income and conversions — from your accounts in order (taxable → traditional → Roth by default), and picks the conversion schedule that maximizes after-tax wealth at the end. It still simplifies real tax law: a single real return; Social Security taxed at a flat fraction; long-term gains taxed at a flat rate (no 0%-bracket harvesting yet); and state income tax either as one flat rate you enter or, under Advanced assumptions, your state's real brackets — even then it ignores local and city income taxes, age-based deductions, and state-specific capital-gains rules, and the prefilled brackets are a starting point to check, not tax advice. IRMAA, NIIT and the ACA premium tax credit can be modeled (2026 figures, off by default — see Advanced assumptions); dividend tax-drag is not. The federal age-65+ standard deduction and the 2025–2028 senior deduction ($6,000 per person 65+, shrinking above $75k of MAGI single / $150k married) are applied by default; a married couple counts as two people of the same age. Pre-59½ withdrawals from the IRA incur the 10% penalty. Pre-59½ Roth withdrawals are penalty-free up to the amount you enter as already eligible (your contributions and conversions at least five years old) plus each conversion this plan makes once it is five years old — the conversion ladder; beyond that they are penalized. The conversion itself is never penalized. 72(t) substantially-equal payments and the Rule of 55 are not accounted for. For a married couple, both spouses are assumed to be the same age and the plan never switches to single filing after a death. Results depend entirely on your assumptions. Confirm any plan with a qualified tax professional before acting. Built by Kind of Lost.
How this works
A Roth conversion means paying income tax now on money in a traditional IRA or 401(k) so it can grow tax-free in a Roth account for the rest of your life. But conversions don't happen in a vacuum — they compete with your living expenses, your capital gains, and which account pays the tax bill, for space in your yearly income.
This calculator treats the whole picture as one optimization problem instead of solving conversions in isolation. It's a linear program — built with Python, PuLP, and the CBC solver, and a mixed-integer one when you switch on the IRMAA, NIIT or ACA options — that plans your full retirement cash flow at once: it funds your living expenses every year, decides which account pays for that spending and for the tax on your conversions and withdrawals, and finds the conversion schedule that leaves you with the most money after tax at the end of the horizon, not just the lowest conversion-tax bill.
It also handles pieces most free calculators skip: capital gains on your brokerage account, split into long-term and short-term and taxed at their own rates; an optional withdrawal order the optimizer can choose instead of a fixed taxable-then-traditional- then-Roth sequence; and a "spend it down" mode that finds the most you can spend every year while draining every account to roughly zero by the end.
It's built for people within a few years of retirement or already retired, with meaningful balances across traditional, Roth, and taxable accounts, who want an answer built on real optimization math rather than a spreadsheet rule of thumb. It's not a substitute for a CPA or financial planner — local income taxes aren't included — but IRMAA, NIIT and the ACA subsidy cliff are there under Advanced, and it's a real, free starting point. For the reasoning behind the model, see when a Roth conversion makes sense and the linear-program math behind this calculator.
Need a single-year number instead of a plan? Two quick calculators use the same 2026 figures: the retirement withdrawal tax calculator (federal tax on an IRA or 401(k) withdrawal, and your bracket) and the IRMAA calculator (the Medicare surcharge your income triggers).
Roth conversion ladder calculator
If you retire before 59½, a conversion ladder is the usual way to reach IRA money without the 10% penalty: convert some every year, and each conversion can be withdrawn penalty-free once it's five years old. This calculator plans the ladder for you. Set your starting age below 59½ and enter any Roth money that is already penalty-free (contributions, plus conversions at least five years old) under Account balances. Before 59½, the plan can then draw from the Roth up to that amount plus each of its own conversions once they're five years old. Anything beyond that is penalized, so the optimizer avoids it unless it's still worth it.
The first five years are the hard part: nothing the plan converts is reachable yet, so spending has to come from the brokerage account, other income, or Roth money that's already eligible. If the plan can't fund those years, the result tells you. It doesn't model the other early-access routes, 72(t) payments and the Rule of 55.
Roth conversion breakeven
The usual breakeven question is how many years a conversion needs before it pays off. Mostly, the answer depends on tax rates, not years. If you pay the conversion tax out of the IRA itself and your rate later is the same as your rate now, converting is a wash no matter how long you wait: tax-free growth on the smaller Roth equals taxed growth on the bigger IRA. Time only starts to matter when you pay the tax from your brokerage account (the money that goes to the IRS would otherwise keep growing in a taxed account), or when your rate later is higher than your rate now.
So this calculator doesn't give you a breakeven year. It asks for the rate your leftover IRA will be taxed at later, by you or your heirs (Future tax rate on un-converted IRA), and your planning end age, and converts only as much as pays off by that age. To test a shorter horizon, lower the end age and run it again. If the conversions shrink or disappear, you have your answer.
Frequently asked questions
How is this different from a simple Roth conversion calculator?
Most Roth conversion calculators only decide the yearly conversion amount and assume your other accounts just grow untouched. This tool plans your whole retirement cash flow at once: living expenses, withdrawal order, and capital gains on your brokerage account. It finds the conversion schedule that produces the most money in your pocket after tax, not just the lowest conversion-tax bill in isolation.
What does "maximize after-tax wealth" mean, exactly?
It compares every plan by what's left across your traditional IRA, Roth IRA, and taxable brokerage at the end of your horizon, after subtracting the tax you'd still owe on the traditional balance and the embedded capital gain in the brokerage account. That number is your after-tax wealth, and it's what the optimizer maximizes.
What is the "spend it down" mode?
Instead of you specifying a living-expense number, this mode asks the solver for the highest constant amount you can spend every year, in today's dollars, while still funding taxes and RMDs, such that all three accounts land at roughly zero by your planning end age. It's a die-with-zero style plan rather than a wealth-maximizing one.
Does it really model my state taxes?
Two ways. By default it applies one flat rate you type in — a rough estimate, and the right answer for the nine states with no income tax. Under Advanced assumptions you can pick your state instead and get its real graduated brackets and standard deduction, prefilled and fully editable, plus switches for whether your state taxes Social Security and how much retirement income it excludes. Those last two are deliberately left to you: state retirement rules are where the answer actually turns, we don't ship them, and guessing them for you would be worse than asking.
What it still doesn't do: county or city income taxes (ten states have them, and Maryland's are large), age-based deductions, or state-specific capital-gains treatment. And the prefilled brackets are a convenience to check against your state's own tables — not tax advice.
What isn't included in this calculator?
It can model IRMAA (the Medicare Part B/D income surcharge, on the real two-year lookback, as the cliff it actually is), the 3.8% Net Investment Income Tax and the ACA premium tax credit with its 400% poverty-line cliff — all on 2026 figures, all switched on under Advanced assumptions rather than by default, so the ordinary run stays instant. If a plan would have tripped IRMAA or NIIT, the notes under the result say so. The 2025–2028 senior deduction ($6,000 per person 65 or older, shrinking above $75,000 of MAGI single / $150,000 married) is on by default, so a conversion that costs part of it is priced in. Not modeled: 0%-bracket capital-gains harvesting, dividend or interest tax-drag on the brokerage, 72(t) substantially-equal payments, and the Rule of 55. Before 59½, Roth withdrawals are penalty-free up to the amount you enter as already eligible plus each of the plan's own conversions once it is 5 years old (the conversion ladder); anything beyond that is penalized. It uses a single real rate of return for every account and a flat long-term capital-gains rate; state tax is either one flat rate or, under Advanced assumptions, your state's real brackets. Treat the output as a starting point to bring to a CPA or financial planner, not a final plan.