Blackjack Insurance: Why It Is Always Wrong
Insurance pays 2:1 on an event that happens about 30.9% of the time. That is a 7.4% house edge — worse than double-zero roulette. The math, including even money on your own blackjack.
When the dealer shows an ace, you are offered insurance: a side bet of up to half your original wager, paying 2:1 if the dealer’s hole card is a ten-value card.
Decline it. Every time. Insurance carries a house edge of about 7.4% in a six-deck game — worse than American roulette, worse than most carnival games, and roughly seventeen times the edge of the blackjack hand you are already playing.
The arithmetic
In a six-deck shoe there are 312 cards, of which 96 are ten-value (tens, jacks, queens, kings). The dealer’s ace is face up, leaving 311 unseen cards from the point of view of someone with no other information.
P(hole card is a ten) = 96 / 311 = 30.87%
Insurance pays 2:1. For the bet to break even, that probability would need to be 33.33%. Expected value on a 1-unit insurance bet:
(0.3087 × +2) + (0.6913 × −1) = 0.6174 − 0.6913 = −0.0739
A loss of 7.39 cents per dollar, or a house edge of 7.4%.
The gap is not subtle and it is not close. Insurance needs a one-in-three shot and gets roughly a three-in-ten.
| Game | House edge |
|---|---|
| Blackjack, basic strategy, 3:2 | 0.43% |
| Baccarat, banker | 1.06% |
| Roulette, single zero | 2.70% |
| Roulette, double zero | 5.26% |
| Blackjack insurance | 7.39% |
| Craps, any craps | 11.11% |
“Even money” is the same bet
If you hold a natural and the dealer shows an ace, you will be offered even money — a guaranteed 1:1 payout instead of the usual 3:2, taken before the dealer checks the hole card.
It sounds like a different offer. It is arithmetically identical to taking insurance for the maximum, and it is settled at the same moment.
Decline it, and you hold a natural against a dealer ace. You have an ace and a ten in your hand, so 95 of the 309 unseen cards are tens:
P(dealer also has a natural) = 95 / 309 = 30.74%
- 69.26% of the time the dealer does not, and you are paid 1.5 units
- 30.74% of the time they do, and the hand pushes — you get your stake back, net 0
EV = (0.6926 × 1.5) + (0.3074 × 0) = 1.0389 units
Even money guarantees exactly 1.0 unit. Taking it costs you about 3.9% of the hand, every time you take it.
The pitch is persuasive because it removes an unpleasant feeling — the push on your best hand. But a push is not a loss. You are paying a real 3.9% premium to insure against an outcome that costs you nothing.
Why the offer exists at all
Insurance is the most profitable optional bet on the blackjack table, and it is offered at the exact moment the player is most anxious. The dealer shows an ace, you are holding something you would rather not lose, and a hand is extended offering to make the worry go away for half a bet.
Note also that the dealer is required to offer it and, in many casinos, to say the word “insurance”. Nobody is doing anything improper. It is simply a bet with a large edge, presented at the moment it will be accepted most often.
The one exception
Insurance becomes a positive-expectation bet when more than one third of the unseen cards are ten-value. In Hi-Lo terms that is a true count of about +3 or higher.
This is the single most valuable deviation available to a card counter, and it is the reason counters take insurance in situations where basic strategy players never should. It requires tracking every card dealt since the shuffle and dividing by the estimated decks remaining.
Absent that, you have no information about the hole card beyond the base rate — and the base rate says no.
Practical rule
Never take insurance. Never take even money. There is no hand you can hold, no upcard pattern, and no run of results that changes this without a count. The dealer will ask, and sometimes ask twice. The answer is the same both times.
Next: the complete basic strategy chart · how rule variations change the edge