401(k) Calculators
Roth or 401(k) Calculator
Compare Roth vs. Traditional 401(k) contributions side by side — or model converting an existing Traditional balance to Roth — using the one number that actually decides the answer: your tax rate now vs. your tax rate later.
Compare Roth and Traditional
The "don't convert" total includes investing the conversion tax you didn't pay today in a side account, for a fair apples-to-apples comparison. Assumes a constant, smooth rate of return.
The one number that actually decides Roth vs. Traditional
Not your income. Not your age. Just this.
If your tax rate today equals your tax rate in retirement, Roth and Traditional produce the exact same after-tax result — a widely-taught but often-missed fact. The entire comparison collapses to one question:
Future tax rate > current tax rate → Roth wins
Future tax rate < current tax rate → Traditional wins
Future tax rate = current tax rate → identical result
Growth rate and years don't change which one wins — they only change by how much, since the same growth factor applies to both sides of the comparison equally.
Roth or 401(k): how the comparison actually works
A roth or 401k calculator, roth vs traditional 401k calculator, or roth or traditional 401k calculator — all the same question — should compare apples to apples: the same pre-tax dollar, contributed two different ways. With Traditional, you contribute the full pre-tax amount and pay tax on it (and its growth) when you withdraw. With Roth, you pay tax on that same dollar today, so less of it actually goes into the account, but nothing is taxed again later.
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Why this is really a bet on future tax rates
Most people default to Traditional because the upfront tax deduction feels good, or default to Roth because "tax-free forever" sounds appealing — but neither instinct is actually the deciding factor. The deciding factor is a prediction: will your tax rate in retirement be higher, lower, or the same as it is today? Common reasons future rates end up higher: a paid-off mortgage removing a deduction, required minimum distributions pushing you into a higher bracket than you planned, or simply expecting tax rates in general to rise. Common reasons they end up lower: retiring with meaningfully less taxable income than during your working years.
Converting an existing Traditional balance to Roth
A 401k to roth ira conversion calculator, 401k to roth conversion calculator, convert 401k to roth calculator, convert 401k to roth ira calculator, traditional 401k to roth 401k conversion tax calculator, or 401k to roth ira conversion tax calculator question is a related but distinct calculation from the contribution choice above: instead of choosing how to save going forward, you're deciding whether to pay tax now on money that's already in a Traditional account, converting it to Roth. The same future-vs-current-rate logic applies — but only if the tax on the conversion is paid from money outside the retirement account. Paying the conversion tax out of the converted balance itself shrinks what actually reaches the Roth account and changes the math meaningfully in Traditional's favor.
Roth 401(k) vs. Roth IRA
A roth ira vs 401k calculator or 401k vs roth ira calculator search is actually asking a different question than this page answers — that's a choice between account types (a workplace plan vs. an individual account you open yourself), not between Roth and Traditional tax treatment. You can have a Roth 401(k) through your employer and a separate Roth IRA on your own; they're not mutually exclusive, and each has its own contribution limits and rules.
The equal-tax-rate equivalence is a well-established result in retirement planning math, consistent with IRS rules on Roth and Traditional 401(k) tax treatment. This is a planning comparison, not tax advice — a qualified tax professional can help estimate your actual future bracket.
Frequently asked questions
Before you pick a box on your enrollment form.
Is Roth or Traditional 401(k) better?
Neither is universally better — it depends entirely on whether your tax rate will be higher or lower in retirement than it is now. Roth wins if your future rate is higher; Traditional wins if it's lower; they're identical if the rates match.
Does my employer match go into the Roth or Traditional portion?
Employer matching contributions are always placed in a Traditional (pre-tax) account, regardless of whether your own contributions are Roth or Traditional — you'll owe tax on the match and its growth when you withdraw it.
Should I convert my 401(k) to Roth if I'm changing jobs?
That depends on the same future-vs-current tax rate question as any other conversion decision, plus whether you have outside funds to cover the conversion tax bill without touching the retirement money itself.
Can I contribute to both Roth and Traditional 401(k) in the same year?
Yes — most plans let you split contributions between both. Your combined contributions across both still count toward one shared annual IRS limit.
Is a Roth 401(k) the same as a Roth IRA?
No — a Roth 401(k) is the Roth option inside your employer's workplace plan, while a Roth IRA is a separate individual account you open yourself. They have different contribution limits and rules, and you can have both at once.