How Positive Expected Value (EV)
Works in Sports Betting
Last updated: October 21, 2025
The complete guide to understanding expected value, calculating EV, and finding profitable betting opportunities that give you a mathematical edge.
What is Expected Value in Sports Betting?
Expected Value (EV) is the mathematical foundation of profitable sports betting. It represents the average amount you can expect to win or lose per bet over time. When you have positive expected value (+EV), you have a mathematical edge over the sportsbook.
Key Concept
Positive EV = Long-term Profit
Even if you lose individual bets, consistently betting on +EV opportunities will make you money over hundreds of bets.
Think of EV as your "edge" - the percentage advantage you have over the house. While casinos and sportsbooks are designed to have a house edge, +EV betting flips this dynamic, giving you the mathematical advantage.
The Expected Value Formula
The Formula
EV = (Probability × Win Amount) - (1 - Probability) × Bet AmountPositive EV (+EV)
You have a mathematical edge. Bet this!
Negative EV (-EV)
The sportsbook has the edge. Avoid this bet.
Zero EV (0 EV)
Fair odds. No edge for either side.
Real Example
This bet has positive EV, meaning you expect to profit $62.50 on average for every $100 bet.
The Challenge: Finding True Probability
The biggest challenge in EV betting isn't the math - it's finding the true probability of an outcome. Sportsbooks don't give you fair odds; they add a "vig" (vigorish) to ensure they profit.
Sportsbook Odds
The extra 4.8% is the sportsbook's vig - their built-in profit margin.
True Odds (No Vig)
True probabilities add up to 100% - no vig, no built-in house edge.
How OpenWager Finds True Probability
Market Analysis
Analyze odds across multiple sportsbooks to find consensus
AI Modeling
Machine learning models predict true probabilities
Vig Removal
Remove sportsbook margins to reveal true odds
Types of +EV Opportunities
Line Shopping
Different sportsbooks offer different odds for the same game. Finding the best line can create +EV opportunities.
Line Movement
Lines move as money comes in. Getting early action on sharp line movements can be +EV.
Arbitrage
Betting both sides of a game at different sportsbooks to guarantee profit regardless of outcome.
Model Disagreement
When your model's probability differs significantly from the sportsbook's implied probability.
Timing Edge
Getting odds before they adjust to new information (injuries, weather, etc.).
Promotional Offers
Taking advantage of bonuses, free bets, or enhanced odds that create +EV situations.
Bankroll Management for +EV Betting
Having +EV bets is only half the battle. Proper bankroll management ensures you can survive the inevitable losing streaks and maximize long-term profits.
Kelly Criterion
The Kelly Criterion tells you the optimal bet size based on your edge and bankroll:
Kelly % = (bp - q) / b(e.g., +150 = 2.5 - 1 = 1.5)
(e.g., 65% = 0.65)
(e.g., 1 - 0.65 = 0.35)
Conservative Approach
Quarter Kelly
Bet 25% of Kelly recommendation for safety
Fixed Percentage
Bet 1-3% of bankroll regardless of edge
Risk Management Rules
Never Risk More Than 5%
Even on the strongest +EV bets
Set Stop-Loss Limits
Stop betting if you lose 20% of bankroll
Common +EV Betting Mistakes
Mistake #1: Confusing EV with Win Rate
A bet can have +EV even if it loses. EV is about long-term expectation, not individual outcomes.
Mistake #2: Overbetting Your Edge
Betting too much on +EV opportunities can lead to ruin even with an edge.
Mistake #3: Ignoring Market Width
Wide markets often indicate sharp action. Narrow markets are usually sharper.
Mistake #4: Not Shopping Lines
Different sportsbooks offer different odds. Always find the best line available.
Mistake #5: Chasing Losses
Increasing bet sizes after losses is a recipe for disaster, even with +EV bets.
Mistake #6: Not Tracking Results
You can't improve what you don't measure. Track your EV bets and performance.
Ready to Start Finding +EV Picks?
Understanding EV is just the beginning. Our AI-powered platform does the heavy lifting, finding +EV opportunities across all major sportsbooks in real-time.