Every Common Mistake, Priced
Updated
Advice about blackjack mistakes is usually ranked by how annoying they are. We ranked them by what they cost, by recomputing the entire game with each mistake applied. The most expensive one is also the most common, and it is not the one people warn you about.
- Refusing to take a card that could bust: +3.03%.
- Never doubling down: +1.37%.
- Never splitting: +0.51%.
- Always taking insurance: +0.29%.
The table
Six decks, dealer stands on soft 17, double on anything, DAS, no surrender, blackjack pays 3:2 — a house edge of 0.46% with correct play. Each row is the whole game recomputed with that one habit applied and everything else played correctly.
| Mistake | Costs you | House edge becomes |
|---|---|---|
| Plays like the dealer | +3.808% | 4.264% |
| Never risks a bust | +3.034% | 3.490% |
| Never doubles down | +1.369% | 1.825% |
| Never splits a pair | +0.512% | 0.968% |
| Always takes insurance | +0.285% | 0.741% |
| Doubles 10 and 11 only | +0.173% | 0.629% |
The expensive one nobody warns you about
Refusing to hit a hand that could bust costs 3.03% — more than a 6:5 payout, more than the dealer hitting soft 17, more than every bad table rule put together.
It survives because busting feels different. You lose immediately, visibly, and it was your decision. Standing and losing later feels like the dealer’s fault. The money is identical. The full calculation is here.
And the one everyone does warn you about
Insurance costs 0.29% if you take it every time. That is real, and it is roughly a tenth of what refusing to bust costs.
It gets the attention because it is a discrete moment with a dealer asking you a question. The habits that cost ten times more happen silently. Insurance in full.
What to fix, in order
1. Hit your stiff hands when the chart says to. This is the whole game.
2. Double when you should. Costing 1.37%, it is the second biggest leak and the easiest to fix — there are only about a dozen cells.
3. Split aces and eights, always. Never split tens or fives.
4. Decline insurance.
Everything else is worth less than a tenth of a percent. The chart for your table covers all of it.
Keep reading
By Martin Kosek · every number on this site is computed by us, not copied.
← Back to guides