Expected Value (EV)
5 min read · Free
What Expected Value Is
Expected value (EV) is the average outcome of a repeated bet over a large number of trials. A positive EV bet makes money over time. A negative EV bet loses money over time. The variance — whether you win or lose any individual bet — doesn't change the long-run result.
Every bet you place has an EV. Most casino bets and sportsbook bets have negative EV — the house builds in a margin that means the average bettor loses. Matched betting is designed to flip that.
The Formula
EV Formula
EV = (probability of winning × profit if you win) − (probability of losing × loss if you lose)
A concrete example with a standard −110 bet:
Bet $110 to win $100 at −110. Implied probability: 52.4% chance of winning.
EV = (0.476 × $100) − (0.524 × $110)
EV = $47.60 − $57.64
EV = −$10.04 per $110 bet (≈ −4.6%)
The book earns roughly $4.60 per $100 risked in the long run. That's the vig.
Why Matched Betting Is Positive EV
A matched bet converts a promo into a guaranteed outcome — the profit is locked in before the game starts. EV doesn't require probability because the result is already known:
$50 bonus bet, hedged to lock in $25 profit
Team A wins: +$25
Team B wins: +$25
EV = +$25 (certain, not probabilistic)
The bonus bet added $50 of free value into the market. Even after paying the vig on the hedge, a net positive remains. The promo outweighs the book's margin.
EV vs. Variance
Positive EV doesn't mean you win every bet — it means you profit on average over many bets. A +EV bet can still lose. Variance is the spread of outcomes around the EV.
Matched betting has near-zero variance because the outcome is hedged. You don't need a large number of trials to realize the expected profit — you realize it on every single completed offer. That's what makes it distinct from +EV betting strategies that require running thousands of bets to see the EV materialize through the noise.
Negative EV to Avoid
Not every promo produces positive EV. Watch for:
- High min-odds requirements. A qualifying bet restricted to odds of −200 or longer forces you into markets where the spread between two books is wide, increasing hedge cost.
- Short expiry windows. A promo that expires in 24 hours may pressure you into placing the hedge at poor odds. Bad odds reduce your net EV.
- Playthrough requirements. Casino-style wagering requirements (e.g., "wager the bonus 5× before withdrawal") on sports promos turn a positive-EV offer into a negative one. Rare in sports betting, but they exist.