Core Rule
Insurance is offered when dealer shows an Ace. You bet half your original stake that the hole card is a ten-value card.
Break-even for a 2:1 payout is 1 in 3 (33.33%). If ten density is below that, insurance is losing.
Practical Guidance
- Basic strategy player: decline insurance.
- Counter: insurance can be correct at sufficiently high true counts.
- Do not confuse insurance with "even money"; they are the same decision mathematically.