EXPECTED VALUE GUIDE
Expected value and implied probability explained
Expected value combines the estimated chance of an outcome with its price. It describes a theoretical average across repeated comparable outcomes, not the result of a single selection.
Probability is only half the comparison
An 80% chance can sound attractive, but a price that requires a 90% win rate to break even would have negative expected value under that estimate. A higher probability does not automatically mean better value.
Read the player prop probability guide for how lines and confidence affect the event being estimated.
Convert American odds to break-even probability
For negative odds −A, the break-even probability is A / (A + 100). For positive odds +B, it is 100 / (B + 100). These formulas assume a win-or-loss outcome with no push.
At −110, the break-even probability is 110 / 210, or about 52.38%. At +150, it is 100 / 250, or 40%. A quoted break-even probability includes the price’s margin; it is not automatically a fair estimate of the event’s chance.
A worked expected-value example
Suppose a hypothetical event has a 55% estimated chance and a −110 price. For each $1 risked, a win earns about $0.909 in profit and a loss loses $1.
Expected net value = (0.55 × $0.909) − (0.45 × $1) ≈ +$0.05 per $1 risked. This is about +5% theoretical expected value, conditional on the probability estimate being accurate.
This is a mathematical example, not a recommended selection. If the true probability were 50%, the same price would have negative expected value.
Pushes, correlation, and model error
With a refunded push, expected net value uses win probability × net win profit minus loss probability × stake; a push contributes zero net profit. Market settlement rules can differ.
For multiple selections, prices and the joint chance of success both matter. Related selections cannot safely be treated as independent. Small errors in a probability estimate can change the sign of expected value.
Use estimates with their limitations
Explore available lines in the NFL leg builder, then review live and historical model results. Limited player history, injuries, role changes, and stale prices can affect the comparison.
FairMetrik provides statistical research and does not place or accept wagers. Positive estimated value does not guarantee profit. See responsible use.