Expected value & +EV betting
What expected value means, the formula SmartStake uses to compute it, and why a long-run edge beats single-bet variance.
What expected value is
Expected value, or EV, is the average result you would get from a bet if you could place it an unlimited number of times. A bet has positive expected value — positive EV, or +EV — when the odds a sportsbook offers pay more than the bet's true probability of winning warrants. Over a large enough sample those bets are profitable on average, even though any single one of them can lose. Negative EV is the mirror image, and it is what most casual betting amounts to: the bookmaker's margin means the average bettor tends to lose over time.
SmartStake's entire purpose is to surface the bets sitting on the positive side of that line. It does this by estimating each bet's true win probability — the no-vig fair odds — and comparing it against the price a book is actually offering. When the offered price is longer than fair, the gap is your edge.
The formula
SmartStake expresses every edge with one calculation:
EV = (decimal odds × fair win probability) − 1
The result is a fraction of your stake, shown as a percentage. A bet listed at 3% EV returns, on average, three cents per dollar staked across a large sample. The two inputs are the book's decimal odds and the fair win probability that comes from devigging the sharpest available prices — so the accuracy of your EV is only ever as good as the fair probability behind it.
Why the long run is what matters
A +EV bet is not a prediction that this bet will win. It is a statement about the average. Variance — the swing of wins and losses around that average — dominates any short stretch, and a genuine edge can sit underwater for dozens of bets before the math asserts itself. This is why volume and discipline matter more than any single result, and why bankroll management exists: to keep you in the game long enough for the average to arrive.
Edge is found, not felt
A bet feeling like a winner is irrelevant to its EV. Trust the fair price and the sample, not the outcome of the last bet.
The practical workflow — how SmartStake finds these bets and presents the edge — lives in Finding positive EV bets. To understand where the fair win probability comes from in the first place, read No-vig fair odds & the hold and Win probability.
- Odds, prices, expected value, conversion rates, and profit figures shown are estimates based on the last data we retrieved. They can change at any time — confirm the current price at the book before you bet, as odds may move and entry errors can occur.