EV = (win% × profit) − ((1 − win%) × stake). A positive EV means the bet is priced in your favor. EV does not tell you whether a single bet will win — it tells you whether the bet is worth making repeatedly.
Math & probability
Expected value (EV)
The average profit per bet if you could replay the same situation thousands of times.
Example
+EV bets over time grow your bankroll; -EV bets shrink it, no matter how often they hit.
Related terms
Kelly criterion
The mathematically optimal stake size given your edge. Most sharp bettors use a fractional version.
Implied probability
The win probability baked into a given odds line, as a percentage.
Closing line value (CLV)
The difference between the line you bet and the line at game time. The single best measure of long-term skill.