What you are actually betting on
Insurance is presented as protection for a good hand. It is not connected to your hand at all. It is a separate wager, at half your original stake, that the dealer's face-down card is a ten.
It pays 2:1, so it needs to win one time in three to break even. Ten-valued cards are sixteen of every fifty-two, which is a little under one in three.
The computed cost
| Game | Chance the hole card is a ten | Break-even | House edge |
|---|---|---|---|
| Six-deck shoe | 31.07% | 33.33% | 6.80% |
| Infinite deck | 30.77% | 33.33% | 7.69% |
| Single deck | 32.65% | 33.33% | 2.04% |
Those figures assume the three visible cards, your two and the dealer's ace, contain no tens. That is the composition most favourable to the bet. Hold a ten yourself and it gets worse, because one of the cards you need is already face up in front of you.
So insurance loses money even in its best case, on every deck size, before you account for the hands where you actually hold tens.
Even money is the same bet
When you hold a blackjack against a dealer ace, the dealer will offer even money: a guaranteed 1:1 instead of the 3:2 you would get if the dealer has no blackjack.
This is insurance wearing a different name, and the arithmetic is identical. Taking it converts a hand worth more than even money on average into exactly even money. On a 3:2 table, decline it.
The one exception
Insurance becomes profitable only when you know the remaining shoe is unusually rich in tens, which means counting cards. For anyone not counting, it is a bet with a 6.8% edge offered at the worst possible moment, when you have a good hand and feel like protecting it.
The correct basic-strategy answer is short: never take insurance, and never take even money. Our basic strategy chart has no insurance column because there is no decision to make.
Frequently Asked Questions
- Should I ever take insurance?
- No, unless you are counting cards. It costs 6.8% on a six-deck shoe even in the most favourable card composition.
- Is even money different from insurance?
- No. Taking even money on a blackjack against a dealer ace is arithmetically the same bet, and it is equally bad on a 3:2 table.
- Why does it feel like the right move?
- Because it is offered when you have a strong hand and the dealer shows an ace. The bet has no connection to your hand; it is a separate wager on the hole card.
- What are the actual odds?
- About 31.1% of hole cards are tens on a six-deck shoe, against the 33.3% you need to break even at 2:1.
Every figure on this page is computed by an expected-value engine that plays the game out: it derives the dealer's final-total distribution by recursion, evaluates standing, hitting, doubling and splitting at each decision, and takes the best. Rule costs are measured by re-running the whole calculation with the rule changed, not by quoting a published delta. The model assumes independent card draws, which sits a few hundredths of a percent from an exact shoe analysis; the rule differences it produces match published values. Rules vary by table, so read the felt.