Blackjack insurance sounds safe. The maths says otherwise, usually

Should you take insurance in blackjack?

For almost everyone, almost every time: no, don't take insurance. It's offered whenever the dealer's up card is an ace, and it's a side bet that the dealer has blackjack, paying 2 to 1 on half your original stake if they do. That sounds like protection, but run the numbers: in a full, unseen shoe roughly 4 in 13 cards, about 30.8%, are tens, the only cards that make the dealer's blackjack true. Insurance needs that share to be at least 1 in 3, about 33.3%, just to break even. Since a normal shoe starts below that number, insurance is a losing bet on average even before the dealer flips anything.

When is blackjack insurance worth it?

Only when the Hi-Lo true count is about +3 or higher, meaning tens make up at least a third of the remaining shoe. Card counters flip this calculation. As the running or true count climbs, it specifically means more small cards have already come out relative to tens, so the tens remaining make up a larger share of what's left. Once that share crosses roughly a third, insurance flips from -EV to +EV, and skilled counters do take it at that point, treating it as a separate side bet triggered by the count rather than a hand-by-hand instinct. This is one of the few correct deviations from basic strategy that isn't about your own hand at all.

How often does that happen? We dealt 100,000 six-deck shoes to 75% penetration and checked the Hi-Lo true count at the start of every round. It reached +3, the usual insurance trigger, on 8.6% of rounds. The dealer only shows an ace on about one round in thirteen, so a counter gets a correct insurance bet roughly once every 150 hands or so. For everyone else, the answer stays no every single time.

Is even money better than insurance?

No. Even money is mathematically identical to insurance. If you're dealt a blackjack yourself and the dealer shows an ace, you may be offered "even money", guaranteed 1 to 1 instead of the usual 3 to 2, before the dealer checks their hole card. This is mathematically identical to taking insurance on your own blackjack, and carries exactly the same -EV problem in a normal shoe. Declining and simply waiting to see if the dealer also has blackjack is the higher expected-value play in the same situations this calculator covers.

Insurance decisions are one of the few blackjack moments where the count, not the hand in front of you, drives the right call, everything else on a normal hand is covered by the Blackjack AI calculator and the full strategy chart.

Putting it into practice

Three habits cover it.

• Decline insurance and even money by default. Only a player tracking a high true count has a reason to take it.
• Tempted by the side bets too? The side bets house edge page has the numbers.
• Keep the strategy chart handy so every other decision is right as well.