Why this isn't a fair fight — and why that's the point
A dividend ETF and a savings account solve different problems. One is a claim on growing businesses that happens to pay you along the way; the other is a guarantee, dollar for dollar, with no principal risk. This calculator isn't here to declare a winner — it's here to make the after-tax math visible, because the sticker-rate comparison (yield vs. APY) is almost never the real comparison once account type and tax treatment enter the picture.
The account-type lever most people underweight
The same dividend stream is worth more inside a Roth IRA than in a taxable brokerage account, and worth something different again in a Traditional IRA — not because the underlying fund changed, but because of when and how the IRS takes its share. Moving the exact same holding between account types can change its effective long-run return more than most yield-chasing decisions do.
Adjust "Account type" above and watch the ending balance shift with everything else held constant.