Roth vs Traditional Calculator (Simplified)
The whole Roth-vs-Traditional question is one comparison: your tax rate now vs your tax rate in retirement. Enter both and see which wins for each $1,000 contributed — a simplified model, not tax advice.
| Roth: after-tax money at withdrawal | — |
| Traditional: after-tax at withdrawal | — |
| Difference | — |
The entire decision in one line
Tax rate today > rate in retirement → Traditional. Today < retirement → Roth. Equal → mathematically identical.
This surprises people, but the commutative property settles it: $1,000 × growth × (1 − tax) equals $1,000 × (1 − tax) × growth. Only the two tax rates differ — everything else is symmetric.
Who typically lands where
| Situation | Usual answer |
|---|---|
| Early career, low bracket, income rising | Roth — lock in the cheap tax rate |
| Peak earning years, high bracket | Traditional — deduct at the high rate now |
| Uncertain / in between | Split contributions — tax diversification |
What the simple model leaves out
- Roth side benefits: no required minimum distributions, tax-free inheritance, contributions withdrawable anytime — worth something beyond the math.
- Traditional contribution room: maxing the account pre-tax shelters more gross dollars than the same cap post-tax.
- Future tax law: unknowable; splitting hedges it.
This is an educational model, not tax advice — brackets are marginal, states differ, and IRA deduction limits phase out with income. Confirm with a tax professional.
Frequently asked questions
Is Roth or Traditional better?
Purely a bet on tax rates: pay tax now (Roth) if your rate is lower today than it will be in retirement; defer it (Traditional) if today is higher. At equal rates the outcomes are mathematically identical.
Why do the two come out equal at the same tax rate?
Because multiplication order does not matter: taxing before growth or after growth at the same percentage yields the same final amount. The decision is entirely about which rate is lower.
Should young people choose Roth?
Usually — early-career tax brackets tend to be the lowest of a lifetime, making now the cheapest time to pay the tax. It also starts the Roth 5-year clock early.
Can I do both?
Yes, and many planners recommend it: splitting between Roth and Traditional diversifies against future tax-rate uncertainty and gives withdrawal flexibility in retirement.
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Last updated: 2026-07-08