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 the low-income window between when you stop working and when Social Security and required minimum distributions kick in, you convert just enough each year 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 one it has verified near-optimal against a brute-force check on every build, while respecting tax brackets, the two-year IRMAA lookback, the ACA subsidy cliff, and the RMDs still waiting downstream. You get a year-by-year schedule and the lifetime-tax difference in dollars, 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.