What Is Expected Value (EV) in Sports Betting?

The core idea: are you getting paid fairly?

Every bet you place is a financial transaction. You are giving money to a sportsbook in exchange for a payout promise. Expected Value (EV) answers a simple question: is that deal mathematically in your favour or against you?

A positive EV bet means that, on average, you profit. A negative EV bet means that, on average, you lose. The individual outcome of any single bet is random — but over hundreds of bets, EV determines your long-run result more reliably than anything else.

The coin flip that explains everything

Imagine someone offers you a coin flip: heads you win $1.20, tails you lose $1.00. The coin is fair — 50/50. Do you take it?

Yes, obviously. Here is why:

EV = (50% × $1.20) − (50% × $1.00) = +$0.10 per flip

You expect to profit 10 cents on every dollar wagered over time. That is positive EV. Sports betting works the same way — you are looking for situations where the payout is better than the true probability warrants.

How EV is calculated for a sports bet

The formula for EV on a sports bet is:

EV = (Model probability × Net payout) − ((1 − Model probability) × Stake)

For a bet at −110 odds (standard spread/total vig):

• If you bet $1.00, you win $0.909 on a win or lose $1.00 on a loss
• If our model says the team has a 55% true probability: EV = (0.55 × 0.909) − (0.45 × 1.00) = 0.50 − 0.45 = +$0.05 EV per dollar
• That is +5% EV — the number shown on SherlockPicks prediction cards

The implied probability trap

Sportsbooks do not give you the fair odds. They add a margin (the "vig" or "juice") so that −110 on both sides of a bet implies 52.4% for each team — which adds up to 104.8%, not 100%. That 4.8% is the house edge baked into every standard bet.

This is why most recreational bettors lose over time even when they pick winners at a 50%+ rate. To beat the vig, your model needs to be right more often than the implied probability suggests — which is exactly what a positive EV number measures.

EV is a long-run concept

You can lose a +8% EV bet. You can lose three in a row. Variance is real and unavoidable. EV only becomes meaningful over 50, 100, 200+ bets. The appropriate response to a losing streak is not to abandon the approach — it is to check whether the edge has genuinely disappeared or whether you are experiencing normal variance.

SherlockPicks tracks this via the Performance page: real, out-of-sample ROI across every sport and market, not cherry-picked runs.

What makes a "good" EV?

• +2–4% EV: Meets the recommendation threshold. Real edge, worth playing at 1 unit.
• +5–8% EV: Strong. The Hot Edge tier on SherlockPicks. Bet with confidence.
• +8%+ EV: Exceptional signal — or an error. Always sanity-check: is there late injury news? Has the line moved significantly since the prediction was generated?

EV vs Edge — what is the difference?

Edge is the raw probability gap: our estimate minus what the book implies. EV converts that gap into expected profit per dollar, accounting for the payout odds. A +6% edge on a moneyline underdog pays more than +6% edge on an even-money spread bet — EV captures that difference. Both numbers appear on prediction cards and work together as a filter.