Roth Conversion Calculator

See what moving money from a traditional IRA or 401(k) into a Roth actually costs — and saves — over your whole retirement, one bracket-filling year at a time.

A Roth conversion moves money out of your tax-deferred accounts and into a Roth, paying income tax on the amount now so it — and everything it earns afterward — grows and comes out tax-free. Done in the right years and in the right size, a series of conversions can shrink a lifetime tax bill by tens or hundreds of thousands of dollars. Done blindly, it can waste the low-tax years you'll never get back, or spill into a higher bracket and cost more than it saves. The difference is entirely a question of how much to convert and when — which is exactly what a calculator should answer for your own numbers, not a rule of thumb.

What a conversion ladder actually does

The classic move is a conversion ladder: in a low-income year — after you stop working, between jobs, on a sabbatical, or any year before Social Security and required minimum distributions arrive — you convert just enough to fill up a target tax bracket, say to the top of the 12% or 22% band, without tipping into the next one. Each rung is a year; each rung shifts a slice of tax-deferred money into the Roth at a rate you chose deliberately. Fill those years and you arrive at 73 with a smaller traditional balance, smaller RMDs, and a large tax-free Roth you never have to touch.

Why RMDs are the whole reason to bother

Left alone, a large traditional IRA doesn't stay quiet. At 73 the IRS forces required minimum distributions — a rising percentage of the balance every year, taxed as ordinary income whether you need the money or not. For a healthy saver those forced withdrawals can push income high enough to tax more of your Social Security, trigger IRMAA surcharges on Medicare Parts B and D, and drag you into a bracket you spent your career avoiding. Converting earlier, on your terms, drains the traditional balance before the government starts draining it for you. The calculator below models that RMD pressure explicitly, so you can see the surcharge cliffs you're steering around — not just the headline tax rate.

What "optimal" means here

retireclarity's optimizer doesn't just apply a bracket rule — it searches conversion schedules and returns a near-optimal one, while respecting tax brackets, the two-year IRMAA lookback, the ACA subsidy cliff, and the RMDs still waiting downstream. What it maximizes is the money you keep after every tax is paid — and you get it as a year-by-year schedule, with the lifetime tax saved shown alongside, so the recommendation is a number you can inspect, not a black box you have to trust.

Want the deeper background first? Read how a Roth conversion ladder works, the mechanics behind this calculator, and real conversion strategies. Or jump straight to the full Roth conversion optimizer.