Definition
Expected value (EV) is the long-run average outcome of a bet, weighted by the probability of each result. Positive EV means you profit on average; negative means the house does.
Worked example
Say you flip a fair coin and bet $1: heads pays $2, tails loses $1. The EV per bet:
Each bet has an expected value of +$0.50. Over 1,000 flips, you'd expect to be up roughly $500. Random variance means a single session could be far above or below that, but the average converges over time.
Why EV matters in blackjack
Every blackjack decision has an EV. Basic strategy is the rule that always picks the highest-EV option. When the math says "double," it's because the EV of doubling exceeds the EV of hitting. When the math says "surrender," it's because giving up half your bet has a higher EV than playing the hand out.
EV per dollar wagered is the standard unit. It's like a return rate per bet. A positive EV decision is profitable on average; a negative EV decision still loses money but loses less than the alternatives.
Examples
| Decision | EV per $1 |
|---|---|
| Doubling hard 11 vs dealer 6 | +$0.668 |
| Splitting 8-8 vs dealer 6 | +$0.394 |
| Standing on hard 12 vs dealer 4 | −$0.211 |
| Hitting hard 16 vs dealer 10 | −$0.535 |
| Standing hard 16 vs dealer 10 | −$0.540 |
| Surrendering hard 16 vs dealer 10 | −$0.500 |
| Insurance bet (no count, 6-deck) | −$0.075 |
Notice surrender at −$0.500 beats both hit (−$0.535) and stand (−$0.540) on hard 16 vs dealer 10. None of the options are positive EV — that hand is just bad — but surrender is the least-bad. Basic strategy says surrender.
EV vs house edge
House edge is just total EV across all hands and decisions, expressed as a negative percentage. A 0.5% house edge means the average EV of every dollar wagered (across thousands of basic-strategy hands) is −$0.005.
EV is the per-decision lens; house edge is the long-run aggregate. Same math, different scale.
EV in BJNP
The premium tier of Blackjack Navigator Pro shows per-action EV breakdowns: when you face a decision, the app displays the EV of each option (hit, stand, double, split, surrender) so you see exactly why basic strategy recommends what it does.
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