Blackjack Insurance Bets
Blackjack tables typically show the main game rules, payouts and terms for insurance wagers. It may seem odd to see a casino prominently promote a side bet that appears to protect players, since casinos generally feature options that favour the house. That is a good reason to look at the bet more closely. Insurance may sound like a way to improve your position, but its presence at the table does not make it a favourable wager.
What Is the Insurance Bet?
Despite its name, insurance does not protect your current blackjack hand. It is a separate side bet offered when the dealer's exposed card is an Ace.
At that point, the dealer asks if players want to insure against the possibility of a natural blackjack. Taking insurance is entirely optional.
If you take insurance, you can wager any amount up to half your original bet. You may bet less than half, but you cannot exceed that limit.
Insurance pays 2 to 1. If you bet half your original wager and the dealer has a natural blackjack, the doubled insurance payout equals your initial bet, offsetting what you lose on the main hand.
What's Wrong with the Insurance Bet?
Professional blackjack players often call insurance a “suckers' bet” because the dealer gets blackjack less than a third of the time. That means players lose more than two thirds of these side bets.
The wager is essentially a bet that the dealer's hidden card is worth 10. In a 6-deck or 8-deck game, the average distribution is 4 10-value cards for every 9 cards that are not worth 10.
At those proportions, the odds are 9 to 4 against the dealer having a 10-value hole card. Consider a $10 blackjack hand and a long session in which you take insurance 130 times at $5 each time.
Those 130 side wagers would add up to $650. With a statistically even card distribution, you would win 40 bets for 40 x $10 = $400, and lose the other 90 for a total loss of $450. That would leave you down $50 on insurance.
When Should You Make the Insurance Bet?
A 2 to 1 payout can make insurance look appealing, but it is generally worthwhile only when card counting shows an unusually high proportion of 10-value cards in the deck. At 4 10-value cards for every 9 other cards, the player is still at a disadvantage.
At a ratio of 4 10-value cards to 8 other cards, neither side has an advantage, making insurance a fair bet.
If the ratio is 4 10-value cards to 7 or fewer other cards, the advantage shifts to the player and insurance becomes worthwhile.
Without counting cards, declining insurance is generally the best choice. The review notes one possible exception: if more than 5 blackjack hands are dealt in a round and no player has a 10-value card, a 10-value hole card is more likely than usual, which may justify taking insurance.
A Few Words of Caution
Card counting does not help in software-based blackjack at an online casino. The software shuffles automatically after each hand, so no cards stay out of play. For example, in an 8-deck game, each hand uses the full 8 decks.
As a result, each hand in software-based blackjack has the same odds as the previous one, so insurance remains unfavourable. The review recommends counting only when playing in a land casino or at an online live-dealer blackjack table where dealt cards are discarded. The odds can then change as the shoe is played, until it is shuffled again.
A positive expectation means the odds are in your favour over time; it does not guarantee that any particular bet will win.
Situations that make insurance favourable are rare. The review notes that many blackjack games do not deal far enough into the shoe, reshuffling when 3 decks remain.
It also matters how accurately you estimate the number of decks left in the shoe. An incorrect estimate can lead to a mistaken assessment of the odds.
