We compare the after-tax value of converting to a Roth now (paying tax today, then growing tax-free) versus leaving the money in a traditional account (growing now, taxed at withdrawal).

Step by step

1. Roth path: subtract today's tax from the amount, then grow it tax-free for the holding period.
2. Traditional path: grow the full amount, then subtract the expected future tax rate at withdrawal.
3. The difference between the two after-tax values is the Roth advantage (or disadvantage).

The math

roth = amount × (1 − taxNow) × (1+g)^years; traditional = amount × (1+g)^years × (1 − taxLater); benefit = roth − traditional.

Sources & assumptions

• Standard after-tax future-value comparison (public domain).

Note: Nothing proprietary — simplified model (no state tax, IRMAA, or pay-the-tax-from-outside-funds effects).

1. This is an educational comparison, not tax advice. Conversions are taxable events.
2. It ignores state taxes, IRMAA, and the source of funds used to pay the tax. Consult your advisor and tax professional.