Calculating Expected Value: Finding +EV Bets
Expected Value (EV) is the average amount you expect to win or lose on a bet if you could repeat it infinite times. It's the single most important concept in sports betting - more important than any handicapping system or betting strategy. Positive EV (+EV) bets are profitable long-term. Negative EV (-EV) bets lose long-term. Mastering EV calculation lets you identify which bets to make and which to avoid.
The EV Formula
Expected Value = (Probability of Win × Profit if Win) - (Probability of Loss × Loss if Lose)
Example:
Bet $100 on Team A at +150 odds
You assess Team A has 50% chance to win
EV = (0.50 × $150) - (0.50 × $100)
EV = $75 - $50 = +$25
This bet has +$25 EV, meaning on average you profit $25 per $100 wagered. Over many bets, this is highly profitable.
The Challenge: Assessing True Probability
The hard part isn't the math - it's determining accurate win probability. The sportsbook's implied probability isn't your probability - they include vig and may be wrong.
Example:
Book offers Team A at +200 (33.3% implied probability)
Your analysis:
- If you agree with 33.3%: EV is zero (break-even)
- If you think it's 40%: Bet has +EV
- If you think it's 30%: Bet has -EV
EV calculation is only as good as your probability assessment. This is where handicapping skill matters.
Accounting for Vig
Standard -110 odds include ~4.5% vig. This makes most bets -EV unless you have edge.
Example: Coin flip at -110 odds
True probability: 50%
Implied probability: 52.4%
EV = (0.50 × $91) - (0.50 × $110)
EV = $45.50 - $55 = -$9.50
You lose $9.50 per $110 wagered on average = -8.6% EV
To overcome -110 vig, you need >52.4% actual win probability. This is your breakeven point.
Comparing Multiple Bets
EV lets you compare bets of different sizes and odds:
Bet A: $100 at +150 with 50% win probability
EV = (0.50 × $150) - (0.50 × $100) = +$25 = +25% ROI
Bet B: $200 at +110 with 52% win probability
EV = (0.52 × $220) - (0.48 × $200) = $114.40 - $96 = +$18.40 = +9.2% ROI
Bet A has better EV% (25% vs 9.2%), making it the better bet per dollar risked. But Bet B has higher absolute EV ($18.40 vs $25 if you bet same amount).
Prioritize based on your goals: ROI% for efficiency, absolute EV for maximum profit.
Using EV for Bankroll Decisions
EV helps determine optimal bet sizing:
- Higher EV bets deserve larger stakes (see Kelly Criterion)
- Low EV bets should be small or skipped
- Negative EV bets should never be made (except for strategic hedges)
- Compare EV across available bets to allocate bankroll optimally
- Track EV of all bets to measure your handicapping skill over time
EV vs Actual Results
Critical concept: EV is long-term average, not prediction.
You can:
- Make a +EV bet and lose (variance)
- Make a -EV bet and win (luck)
- Have losing months while making +EV bets
- Have winning months while making -EV bets
Short-term results don't validate or invalidate EV. A +$25 EV bet that loses was still correct to make. Over hundreds of bets, +EV betting always wins. This is why discipline matters - you must trust the math even when variance goes against you.
Practical EV Application
Calculate EV for every significant bet. Use our EV calculator to quickly assess opportunities. Remember that your probability assessment is subjective - be honest about your uncertainty. If you're not confident in your probability estimate, reduce bet size. Track your long-term results to validate your probability assessments. If your +EV bets consistently lose, either you're unlucky or your probability assessments are wrong. Over 500+ bets, the math reveals the truth. Focus on finding +EV opportunities and sizing them properly - this is the entire foundation of profitable sports betting.