Blackjack insurance: rules, real cost and even money explained

The dealer turns over an ace and a question pops up: would you like insurance? Blackjack insurance looks like protection against the house making blackjack. In reality it is a bet in its own right, with its own odds and its own price, settled before your hand has even been played.

So it pays to know what you are buying before you click. The figures in this article are not a rule of thumb: we calculated the exact probabilities from the composition of the shoe, from one to eight decks, with the dealer's ace and the cards already in your hand taken out.

Insurance in blackjack: a bet on the dealer's hole card

With an ace showing, the dealer has blackjack if the second card is worth 10: a ten or a face card (jack, queen, king). That is exactly what this offer backs. In other words, you are not betting against the dealer's blackjack, you are betting on it.

The name comes from how the two bets combine. Should the dealer turn out to have blackjack, your hand loses, but the side bet makes up for it and the round ends level. No minimum win is ever guaranteed: at best, insurance lets you walk away from a losing hand without a loss.

On the Crazy Dice tables that offer it, the option appears as soon as the dealer shows an ace, before you make any decision. On Evolution's First Person Blackjack, it pays 2 to 1 and is played from an eight-deck shoe that is rebuilt every round.

Blackjack insurance rules: from the offer to the payout

Take a €6 hand at a table of online blackjack in Belgium, facing a dealer ace.

• The amount: the side bet costs half your main bet, so €3.
• The timing: you decide on it first. Hitting, standing, doubling or splitting all come afterwards.
• If the hole card is worth 10: the side bet pays €6 and you get your €3 back, while your €6 hand is lost. Net result for the round: €0.
• If it is not: the €3 is gone and your hand carries on as normal, with everything it can still win or lose.

The 2 to 1 payout is not arbitrary. It is the fair price for something that happens exactly one time in three. The whole question, then, is whether the hole card is worth 10 one time in three. Without any information about the shoe, it never gets there.

Why blackjack insurance never reaches the one-in-three mark

A full deck holds 16 cards worth 10 out of 52. Take out the dealer's ace and 16 out of 51 remain, or 31.4%. The more decks in the shoe, the closer the share gets to 4 in 13, which is 30.8%. Either way, it stays below the 33.3% that would make the bet fair. Here is what the house keeps from every euro placed this way:

• one deck: 5.9%;
• two decks: 6.8%;
• six decks: 7.4%;
• eight decks: 7.5%.

With an eight-deck shoe, €100 put into insurance therefore costs €7.47 on average. For comparison, the main bet on First Person Blackjack returns 99.29% of stakes, leaving the house 0.71%. On the side bet, it takes ten times as much.

Insuring a 20: the wrong instinct

The most common instinct is to insure a strong hand so that a dealer blackjack cannot sweep it away. Yet your two cards come out of the same shoe as the dealer's. If both are worth 10, fewer remain for the dealer, and the bet becomes even less worthwhile.

With eight decks, the cost rises from 7.0% when you hold two low cards to 7.8% with a single ten-value card, and to 8.5% with a 20. From a single deck, the gap widens sharply: from 2.0% to 14.3%, depending on your hand. Your own cards do matter, and the very hand you most want to protect is the one that makes protection most expensive. Against an ace, a 20 simply stands, as all sound blackjack strategies recommend: insurance only adds a cost.

Even money: the same bet under another name

You have blackjack and the dealer shows an ace. Some tables then offer even money: being paid 1 to 1 straight away instead of the usual 3 to 2. The reasoning is the fear that the dealer has blackjack too. Yet in that case your hand is not lost: two blackjacks are a push and your stake comes back.

Run the numbers and even money turns out to be insurance in disguise. Insure a blackjack for half your stake and you win exactly one stake if the dealer has blackjack (push on the hand, insurance paid 2 to 1) and exactly one stake if not (blackjack paid 3 to 2, insurance lost). The outcome is fixed in advance, just as with even money.

That certainty has a price. With eight decks, turning it down returns 1.0387 times your stake on average, against 1 times if you accept. With a €10 blackjack, you are swapping an average win of €10.39 for a guaranteed €10, and giving up 3.9% of your stake each time.

A hundred insurance bets: what the maths shows

If this bet loses over time, why do so many players feel it works for them? Because ‘over time’ is a long stretch. Take a run of 100 insurance bets of €5 from an eight-deck shoe. You need at least 34 wins to finish ahead, while the expected figure is 31, for an average loss of €37.

Even so, around 28% of these runs end in profit. More than one player in four can therefore remember a night when insurance ‘paid off’. Over 1,000 accepted offers, the share of winning runs drops to 4%: the more often you say yes, the clearer the real cost becomes.

When to take insurance in blackjack: the one exception

Insurance only pays its way over time when more than a third of the remaining cards are worth 10. Knowing that means tracking the cards already dealt from a shoe that is played down hand after hand, which is what card counting is all about. At a software table whose shoe is rebuilt every round, the threshold is never crossed, so the answer is always no.

Saying no is not enough to beat the house, but it is the first saving. The rest of the hand is played according to your total, and most of our tables let you practise in demo mode first. Every euro you do not hand over to this bet stays in your balance: at Crazy Dice, the fast-withdrawal casino, a withdrawal from €50 reaches you within minutes once your identity has been checked.

Set your budget before you sit down at a table and stay in charge with the responsible gaming controls in your player area. To play for real money, open your account at the online casino for Belgian players.

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