Your assumptions
Pre-tax amount$10,000
Years invested30
Annual return7%
Tax rate now24%
Tax rate in retirement22%
Capital-gains rate15%
After-tax future value
HSA — taxed never
Assumes qualified medical withdrawals. After 65, non-medical withdrawals behave like a traditional account.
Roth IRA — taxed once
Assumes qualified withdrawals (59½+, 5-year rule met). Taxed once, going in.
Traditional 401(k) — taxed later
Assumes fully deductible contribution, taxed as ordinary income at withdrawal.
Taxable brokerage — no shelter
After-tax in; gains taxed at the capital-gains rate at sale. (Ignores annual tax drag — reality is slightly worse.)
A different question lives in the retirement lab
This tool compares where to put new dollars. Deciding whether to convert existing traditional balances to Roth — paying tax now to buy tax-free later — is withdrawal modeling, and it belongs with the spend-down tools.
Model Roth conversions