Picture this: you’re at the racetrack, and a friend gives you a tip on an underdog horse. The odds seem crazy, but something about it feels right. You decide to take the bet. Later, when the horse actually wins, you’re left wondering—was it just luck, or was there something deeper at play?
That “something deeper” is called Expected Value (EV)—the secret weapon that separates casual bettors from sharp, calculated winners. It’s the mathematical key to finding profitable bets and, if used correctly, can help you beat the bookmakers over time.
Breaking Down Expected Value: What It Really Means
At its core, Expected Value (EV) is a measure of how much you can expect to win (or lose) on average per bet over the long run. It’s a way to quantify whether a bet is favorable (+EV) or unfavorable (-EV).
The formula is simple:
EV=(ProbabilityofWinning×PotentialWin)−(ProbabilityofLosing×AmountStaked)EV = (Probability of Winning × Potential Win) – (Probability of Losing × Amount Staked)EV=(ProbabilityofWinning×PotentialWin)−(ProbabilityofLosing×AmountStaked)
Let’s break it down with a real-world example. Imagine you’re flipping a coin with a friend, and they offer you 2.2x your bet if it lands on heads. Since a fair coin gives you a 50% chance of winning, here’s the math:
- Win probability: 50% (0.50)
- Payout if you win: $10 bet × 2.2 = $22
- Lose probability: 50% (0.50)
- Loss if you lose: -$10
Now, calculating the EV:
EV=(0.50×12)−(0.50×10)=6−5=+1EV = (0.50 × 12) – (0.50 × 10) = 6 – 5 = +1EV=(0.50×12)−(0.50×10)=6−5=+1
A +1 EV means that, on average, you’ll make $1 profit per bet over the long run. This is a positive expected value (+EV) bet—the kind that professional bettors hunt for relentlessly.
How Bookmakers Stack the Odds Against You
The problem is, sportsbooks aren’t in the business of losing money. They adjust their odds to ensure they maintain an edge—also known as the vig or margin.
Let’s say a bookmaker offers odds of 1.90 on both sides of a 50/50 event (instead of the fair 2.00 odds). This means:
- Win probability: 50% (0.50)
- Payout if you win: $10 bet × 1.90 = $19
- Loss if you lose: -$10
EV calculation:
EV=(0.50×9)−(0.50×10)=4.5−5=−0.50EV = (0.50 × 9) – (0.50 × 10) = 4.5 – 5 = -0.50EV=(0.50×9)−(0.50×10)=4.5−5=−0.50
Here, your expected loss per bet is $0.50, making it a -EV bet. This is how bookmakers profit—by shifting the odds slightly in their favor across thousands of bets.
Finding +EV Bets: Where the Real Money Is
Sharp bettors don’t gamble blindly; they identify and exploit +EV opportunities where bookmakers have miscalculated the odds. Here’s how:
1. Spotting Overpriced Odds
Sometimes, sportsbooks make mistakes. Maybe they underestimate a team’s potential or don’t react quickly to injury news. If your personal probability estimate is higher than what the odds imply, you’ve found value.
2. Line Shopping
Not all bookmakers offer the same odds. A bet at 2.10 at one site could be 2.00 at another. Always compare odds to maximize your potential edge.
3. Using Statistical Models
Serious bettors use spreadsheets, simulations, and historical data to find patterns in betting markets. A properly built model can detect inefficiencies in bookmaker odds.
If you’re looking for a platform with competitive odds and a seamless betting experience, 20Bet is a solid choice. With a simple 20Bet login, you can access a wide range of betting markets and find the best opportunities for +EV bets.
The Reality of Beating the Bookmakers
The truth? Even with +EV betting, there’s no guarantee of immediate profits. Variance—short-term swings of good or bad luck—can make or break a bettor’s confidence. However, over hundreds or thousands of bets, positive EV bettors eventually come out ahead.
Imagine a casino running a roulette wheel with a house edge of 5%. Some players might win in the short term, but the casino always profits in the long run. Now flip that equation—if you’re betting with an edge, you become the casino.
Patience, discipline, and a clear understanding of EV are what separate winners from losers.
Betting Smart, Not Just Betting
Betting without understanding EV is like playing chess without knowing how the pieces move. You might get lucky a few times, but the strategy isn’t sustainable.
The key to long-term success is consistently finding +EV bets, managing your bankroll wisely, and embracing the fact that variance is part of the game. Bookmakers don’t want you thinking this way—but that’s exactly why you should.
If you’re serious about winning, it’s time to stop betting on gut feelings and start betting on math.
Because when the numbers are on your side, the bookmakers aren’t.