What is a prop bet?

A prop bet (short for proposition bet) is a wager on something inside a game other than who wins or by how much. A quarterback throwing for over 275 yards, a center grabbing 10 rebounds, which team scores first: none of those settle the game, so none of them are a moneyline, spread, or total.

Team props vs. player props

Props split into two groups. Player props are tied to one athlete's own stats: passing yards, strikeouts, shots on goal, three-pointers made. Team props are tied to one team's performance but still aren't the final margin: total team touchdowns, whether a team scores in the first five minutes, a team's total made threes. Both groups share the thing that makes them props rather than game lines: the bet can lose even though your team wins, and it can win even though your team loses. A few player props, like anytime touchdown scorer, only ever post one side; the price still converts to a chance the same way, but there's no second side to check it against.

Most props post two sides to bet, like a yardage total's over and under, but a few, like anytime touchdown scorer, only list one side to back. Pricing a prop that has no second side to check it against takes a different approach from the one below.

A same-game parlay strings several props (and often a game line) from the same game onto one ticket. Pricing the combination is a different question — the legs aren't independent, since one player's big game often moves another's — but the pricing idea below applies to each leg on its own before the book combines them.

Why props aren't tied to the final score

A spread or total has one outcome baked into the box score: who covered, or whether the combined score cleared the number. A prop's outcome is a line item inside that box score, measured whether or not the game itself was competitive. That's why a prop on a star player can still cash in a blowout, and why a backup quietly having a good game can beat a prop while his team loses by three touchdowns.

It's also why props depend on different inputs than game lines do. A spread mostly needs a good estimate of two teams' relative strength. A player prop needs that, plus how the game script affects one player's workload: a team playing from behind throws more, a team protecting a lead runs more, and a blowout can end a starter's night early.

Why prop markets usually carry more vig

Every two-sided market has some margin built in — that's the vig. A standard -110 game line prices both sides at 110/210 = 52.38%, so the two sides add up to 104.76%: a 4.76-point margin. Removing the vig scales that back to the fair 50/50 split underneath.

Prop markets are usually priced wider than that, because fewer sharp books post a number on, say, a tight end's receiving yards, and the ones that do take less volume on it than on the spread. A market of -125 on the over and -105 on the under implies 125/225 = 55.56% and 105/205 = 51.22%, adding up to 106.78% — a 6.78-point margin, almost two points wider than the plain -110 game line above, for the same reason a less-traded market tends to be priced with more room: there's less competing money correcting it. That's a worked illustration, not a fixed rule — margin varies by book, sport, and how popular the specific market is, so check a market's own two-sided price rather than assuming a number.

The practical result is the same math as any other bet: take whichever side the book prices closer to its fair chance, and expect a wider gap on a prop than you'd see on a moneyline at the same book. How sportsbooks price player props covers how a book turns one projection into a price for every number it offers, and why fewer sharp books trading the market is what pushes that gap wider in the first place.

Settlement when a player doesn't play

Props on a player who's ruled out or pulled before kickoff are usually voided and refunded, not graded. Exact rules on a reduced role, an early exit, or a push vary by book, so check your book's current terms before betting a player who's a game-time decision.

Putting it together

1. Decide whether you're betting the player or the team; that tells you what actually has to happen for the prop to win, independent of the final score.
2. Expect a wider gap between a prop's two sides than a game line's. Use the de-vig calculator on the two prices to see the real margin before you bet.
3. On a yardage or reception stat, check the over against the real distribution, not just a projected average: a skewed stat can make the over look better than it is.
4. Track props the same way as any other bet: log the price you took and compare it with where the market closed. Closing-line value works the same on a player prop as it does on a spread.

Betting is for adults 21+ where legal, with money you can afford to lose.