What Is Expected Value (EV)?
Expected value is the average amount you would win or lose per bet if you placed the same bet thousands of times. A positive expected value (+EV) bet is one where the price offered is better than the true probability of the outcome — so, by definition, its long-run average is a profit. The whole difficulty lives in the phrase “true probability”: a bet is only genuinely +EV if your probability estimate is more accurate than the price, and that is hard to do reliably.
It is the mirror image of a casino. At roulette, every spin has negative expected value for the player — the house edge is built in. A +EV bet is one where the expected value points the other way, toward the bettor. Recognizing when that is genuinely true, rather than only apparently true, is the skill this guide is about.
The Math Behind +EV
The formula is straightforward:
EV = (Win Probability x Profit) - (Loss Probability x Stake)
Example: A sportsbook offers +150 on a team you estimate has a 45% chance of winning.
- Win probability: 45% (0.45)
- Profit per dollar at +150: $1.50
- Loss probability: 55% (0.55)
- EV per dollar = (0.45 x $1.50) - (0.55 x $1.00) = +$0.125 (12.5%)
That is a 12.5% edge — if your 45% estimate is correct. You will not win every bet, but across many bets with a real edge, the average converges toward that expected value. How much to stake on a given edge is a separate question, covered by the Kelly Criterion.
Why Most Bettors Lose
Sportsbooks build a margin (the “vig” or “juice”) into every line. If a game is truly 50/50, they might offer -110 on both sides instead of +100. This ensures the book profits regardless of the outcome.
Most bets carry negative expected value — the bettor is paying the vig on every wager. Even skilled handicappers who pick winners 55% of the time can still lose money if they are always betting at -110. The point isn't just picking winners — it's whether the price paid enough for the risk taken.
How +EV Is Identified: The No-Vig Consensus
The most common method is the no-vig consensus approach:
- Collect odds for the same game from multiple sportsbooks (the more, the better)
- Remove the vig from each book's line to estimate its implied “true” probabilities
- Average the no-vig lines across books to get a consensus fair probability
- Compare each book's price against that consensus — a price that pays more than the consensus implies is where +EV would come from
This works because the combined pricing of many books is usually more accurate than any single one. When a book is an outlier it may be mispriced — but it may also just be noise, which is why the size of the gap and the number of books both matter. A common refinement is leave-one-out: to judge one book's price, build the consensus from the other books, so the comparison isn't circular.
EV Betting vs. Handicapping: What's the Difference?
Traditional handicappers try to predict winners. EV bettors try to find mispriced lines — and those are very different goals.
A handicapper might say “I think the Raptors win this game.” An EV-minded bettor says “The market implies the Raptors have a 42% chance, but I estimate 49% — that gap is where value would be.”
You can be wrong about who wins and still be right about the bet — and right about the bet and still lose it. If a team is priced at +200 (implied 33%) and their true probability really is 40%, that is a +EV bet even if they lose that particular game. The catch, again, is knowing the true probability is 40% and not 33%.
This is why EV-minded bettors track expected value and closing line value rather than win percentage alone. A 48% win rate at plus-money can outperform a 55% win rate chasing -200 favorites — the price matters as much as the result.
The Kelly Criterion: How Much to Bet
Identifying a +EV price is only half the equation. Bet sizing determines whether you profit or go broke — even with a genuine edge.
The Kelly Criterion is the mathematically optimal bet-sizing formula:
Kelly % = (Edge / Odds) × Bankroll
Where edge = your estimated probability minus the implied probability from the odds.
Example: a 4% edge on a +110 line gives Kelly % = 0.04 / 1.10 = 3.6% of bankroll. On a $1,000 bankroll that is a $36 bet.
Most bettors use “fractional Kelly” — a fraction (say 25–50%) of the full Kelly amount — to cut variance while keeping most of the benefit. Sizing is where a genuine edge is protected or squandered.
How Market Efficiency Varies by Sport
Not all markets are priced equally sharply. Two factors drive it: market liquidity (how much attention and money a book puts into a line) and scoring variance (how much luck separates the result from the underlying matchup).
NBA is high-scoring, heavily bet, and liquid, so lines are generally sharp — but they move fast, and early markets and player props get less attention than sides and totals.
NHL is low-scoring, so a single goal is enormous variance on a five- or six-goal game. Overtime adds a near-coinflip element that books price inconsistently across sportsbooks.
College basketball (NCAAB) regular-season lines are often softer than the pros, because books devote fewer resources to pricing hundreds of games; tournament lines are much sharper. See our March Madness betting guide for tournament-specific detail.
Soccer (EPL/UCL) has three outcomes (win/draw/lose), which adds complexity, and it takes larger samples to say anything reliable about how accurately a market is priced.
Common EV Betting Mistakes
Mistake 1: Chasing steam without understanding why. Sharp money moving a line is a signal, not a strategy. Understanding why the line moved matters more than following it blindly.
Mistake 2: Ignoring closing line value (CLV). The closing line is the most accurate reflection of true probability. If you consistently get a better number than where the market closes — positive closing line value — that is evidence your prices were good, regardless of short-term results.
Mistake 3: Too small a sample size. Judging price quality takes hundreds of bets. A 20-bet losing streak means little statistically; a large sample tells you far more than a handful of recent results.
Mistake 4: Treating all +EV prices equally. A 2% gap at -110 and a 12% gap at +200 are both “+EV,” but very different. Bet sizing (see Kelly, above) should scale with the size of the edge, not treat every price the same.
Mistake 5: Using the wrong sportsbooks. Some Canadian books severely limit or restrict winning accounts. Pinnacle is the standard reference for sharp bettors — it accepts action and posts among the lowest margins in the market. Bet365 and Betway are reasonable options before limits tighten. Building a multi-book habit from the start protects your long-term access and your price on every bet.
How EdgeBets Fits In
EdgeBets compares prices across 10+ Canadian-accessible sportsbooks throughout the day and shows the best available number on each game — the line-shopping step from this guide, done for you. It also publishes daily model projections. EdgeBets does not sell picks or promise profits; the aim is to make the best price and an honest projection easy to see.