TALLIVORoth vs Traditional Calculator
The comparison after tax, not the balance — because the balance is the same either way and the tax is the entire question.
Break-even is a retirement rate of 24% — your rate today. Below it, Traditional wins; above it, Roth.
If your marginal tax rate is the same in retirement as it is today, Roth and Traditional produce exactly the same money — $57,853 either way on $10,000 a year for 30 years at 7%. Identical, not close. Traditional comes out ahead only if your retirement rate is lower than today’s, and Roth only if it is higher.
The comparison assumes one marginal rate on the way in and one on the way out, ignores any employer match (which is always pre-tax regardless), and uses the 2026 federal brackets. The break-even retirement rate is simply your current rate.
Why they tie, in one line of algebra
Almost every article on this treats it as a matter of judgment. It is mostly arithmetic, and the arithmetic is short enough to check:
Traditional: contribute C, grow it by (1+r)n, then pay tax on the way out — C × (1+r)n × (1 − tretirement).
Roth: pay tax first, grow what is left — C × (1 − tnow) × (1+r)n.
Those are the same three numbers multiplied in a different order. Multiplication does not care about order, so when tnow equals tretirement the two are the same number. The return rate does not break the tie. The time horizon does not break the tie. Every “Roth grows tax-free!” argument that stops there has quietly forgotten that the Traditional account grew a larger balance in the first place, by exactly the tax you did not pay.
What is left is a single question: will your marginal rate be higher or lower when you take the money out?
What the gap actually looks like
On $10,000 a year for 30 years at 7%, from a 24% bracket today:
| Retirement rate | Traditional | Roth | Difference | Winner |
|---|---|---|---|---|
| 12% | $66,988 | $57,853 | $9,135 | Traditional |
| 22% | $59,376 | $57,853 | $1,522 | Traditional |
| 24% | $57,853 | $57,853 | — | tie |
| 32% | $51,763 | $57,853 | $6,090 | Roth |
| 35% | $49,480 | $57,853 | $8,373 | Roth |
| 37% | $47,957 | $57,853 | $9,896 | Roth |
The row where they tie is the row where the rates match. Everything above it favours Roth and everything below it favours Traditional, and the size of the gap is just the balance multiplied by the difference between the two rates.
The one argument for Roth that is not about tax rates
The $24,500 annual limit caps the dollars going in, not their after-tax value — and that makes the cap quietly favour Roth.
Put $24,500 into a Roth and the whole balance is yours; the tax is already settled. Put $24,500 into a Traditional and you also keep $5,880 of tax you did not pay — but there is no tax-advantaged room left for it, so it goes into a taxable account where its growth is taxed. Over 30 years at 7%, with a 15% rate on the gain, that drag comes to $5,832, even with the tax rates identical and the two accounts tying exactly.
This only matters if you are actually at the cap. Below it, you can always contribute more to the Traditional instead, and the effect vanishes. It is also a floor rather than a ceiling: a real taxable account loses a little more along the way to tax on dividends and distributions, which this does not model.
What this calculator will not do
It will not guess your retirement tax rate. That input decides the whole answer, and it depends on future tax law, how much you withdraw, whether you have a pension or Social Security, and which state you retire to. A calculator that picks one for you is answering a question it made up, and then presenting the result as though it were yours.
It also models one marginal rate rather than a full bracket walk on the way out. Real withdrawals fill the brackets from the bottom, so the effective rate on a Traditional withdrawal is usually lower than the marginal rate — which tilts things toward Traditional more than this comparison shows. To see your own bracket structure, the income tax calculator walks the actual 2026 brackets, and the 401(k) calculator projects the balance itself with an employer match.
Note that a match is always pre-tax and lands in a Traditional account whatever you choose for your own contributions — so the choice is about your money, not the whole account.
Common questions
Is Roth or Traditional better?
Why are they identical when the tax rates match?
What is the break-even tax rate?
Does the contribution limit change the answer?
What tax rate will I actually pay in retirement?
Should I split between both?
How we calculate this
Two expressions, both after tax. Traditional grows the full contribution and applies the retirement rate at the end; Roth applies today’s rate first and grows the remainder. The break-even is read straight off the algebra rather than searched for.
A tie is reported as a tie. When the two rates match, the engine compares the inputs rather than the outputs, so a floating-point crumb in the growth factor cannot invent a winner out of a difference that is mathematically zero. Rate options and the contribution cap come from the committed 2026 federal data, as of 2026-07-22.
Where to go next
Once the account type is settled, project the balance itself with employer matching and the contribution limit — a match is always pre-tax whichever way you choose.
Models one marginal rate in and one out, ignores state taxes, RMDs, the five-year rule and income limits on direct Roth IRA contributions, and assumes tax law does not change. Estimates for general information only — not financial, tax, or investment advice.