Betting Value
What Expected Value Means
Expected value explained with simple math, and why it's the foundation of betting for value instead of chasing winners.
By Jared Narz · · 2 min read
Expected value (EV) is the average amount you'd win or lose per bet if you could place the same bet many times. A +EV bet is one where the payout is bigger than the true risk justifies.
The formula
EV = (win probability × profit if win) − (loss probability × stake)
Illustrative example
You can bet +150 (risk $100 to win $150). You estimate the true win probability at 45%.
EV = (0.45 × $150) − (0.55 × $100) = $67.50 − $55.00 = +$12.50
On average, that bet is worth +$12.50 per $100 risked, if your 45% estimate is accurate. The price implied only 40% (100 / 250), so you're being paid more than your estimate says the risk deserves.
The hard part: estimating true probability
EV is only as good as the probability you plug in. Common approaches:
- Market-based: remove the vig from sharp, low-margin markets to estimate a fair price, then look for books offering better. Tools like OddsJam help with this.
- Model-based: your own projections or ratings.
- Information-based: reacting to news before the market fully adjusts.
What +EV doesn't mean
It doesn't mean the bet wins. A +EV bet at +150 still loses more often than it wins. EV plays out over many bets, which is why bankroll management matters.
Examples are illustrative and use hypothetical numbers. This article is educational content, not financial advice or a guarantee of results. 21+. Bet responsibly.