Insurance
When the side bet becomes profitable for card counters
What Is Insurance?
When the dealer shows an ace, you're offered “insurance” — a side bet of up to half your original wager that pays 2:1 if the dealer has blackjack. It's really a bet on whether the dealer's hole card is a 10-value.
Why Basic Strategy Says Never
In a fresh deck, about 30.8% of cards are 10-value (16 out of 52). Insurance pays 2:1, so you need the dealer to have a 10 more than 33.3% of the time to break even. With a normal deck composition, insurance has a house edge of roughly 7% — one of the worst bets in the casino.
When Counting Changes Everything
A high true count means the remaining deck is disproportionately rich in 10-value cards. At some count, the proportion of 10s exceeds the 1/3 threshold and insurance becomes a +EV bet. The chart below shows exactly where this crossover happens.
Insurance EV vs True Count
Expected value of taking vs declining insurance at each true count
Data points are plotted at TC + 0.5 because the simulation uses floored true counts. A floored TC of N represents a continuous true count in the range [N, N+1), with an average near N + 0.5. The half-step offset reflects this so crossover points appear at their true position on the continuous scale.
Reading the Chart
The green line shows the EV of declining insurance (playing your hand normally). The purple line shows the EV of taking insurance. Where the purple line crosses above the green line is the insurance index — the true count at and above which a counter should take insurance.
For most rulesets, this threshold is around TC +3. Insurance is one of the most valuable deviations because it comes up frequently (any time the dealer shows an ace) and the EV gain per hand is substantial at high counts.
Even Money
“Even money” is offered when you have blackjack and the dealer shows an ace. Taking even money is mathematically identical to taking insurance. The same counting logic applies: take even money only when the count is at or above the insurance index.