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Odds discrepancies between sportsbooks

Why the same bet has different prices at different books, what the gaps tell you, and how bettors use them.

TommyLocks, Nov 3, 3 min read

The same bet doesn’t cost the same everywhere. One sportsbook might have a player’s over at -105 while another has it at -120, or one book’s spread is -3 while another’s is -3.5. Those gaps are odds discrepancies, and they show up on almost every game.

What an odds discrepancy is

There are two kinds:

• Different prices on the same line: Over 22.5 points at -105 at one book and -120 at another.
• Different lines: a total of 228 at one book and 229.5 at another, or a spread of -3 versus -3.5.

Why books disagree

• Each book sets and moves its own lines. They react to the bets their own customers place, and those customers differ from book to book.
• News reaches them at different speeds. When a starter is ruled out, some books adjust within seconds and others take longer.
• Margins differ. Some books build a bigger cut into certain markets, especially player props.
• Promotions and boosts temporarily move a book’s price away from everyone else’s.

What the gaps can tell you

How much the price difference is worth. Every price has an implied probability, the win rate it needs to break even. Over 22.5 at -105 needs 51.2%. The same over at -120 needs 54.5%. Put another way, -105 pays $0.95 profit per $1 and -120 pays $0.83, so the better price pays 14.3% more for the same bet. That’s the % difference the odds screen and discrepancies tab show.

Where the market is heading. When one book moves its line and others follow, the first book often reacted to news or sharp action. A book still sitting at the old number may be slow to adjust.

What the market thinks is fair. When most books cluster around one price and one book is far off, the cluster is usually the market’s estimate of the true chance. The outlier is either slow to move, shading its price on purpose, or reacting to something the others haven’t yet.

How much a half-point matters. Different lines change which outcomes win. In the NFL, where many games land on margins of 3 and 7, the gap between -2.5 and -3.5 can mean a lot. In the NBA, where scores spread out more, a half-point usually matters less, but on totals and player props it still changes how often a bet cashes.

How bettors use them

Line shopping. Placing the same bet at the book with the best price. On a $100 bet, a win at -105 pays $95.24 and a win at -115 pays $86.96: $8.28 more for the same outcome. Those differences add up across a season of bets.

Finding +EV bets. Remove each book’s margin, average the results into a fair price, and compare every book against it. A book whose price pays more than the fair price is offering a +EV bet. (What +EV means explains the math.)

Timing around news. After an injury or lineup change, comparing books shows which ones have adjusted and which haven’t yet.

Middles. When two books have different lines, a bettor can take the over at the lower number and the under at the higher one. With Over 227.5 at one book and Under 229.5 at another, a final total of 228 or 229 wins both bets. Outside that window, one bet wins and one loses, so the result is a small loss from the vig.

Arbitrage. Occasionally prices differ enough that betting both sides at different books locks in a small profit whatever happens. These windows are rare and short, and sportsbooks may limit accounts that bet this way.

Tools for comparing books

• The odds screen in Educated Wagers shows moneylines, spreads, totals and player props (points, rebounds, assists, 3s, double-doubles and triple-doubles) from FanDuel, DraftKings, BetMGM, Caesars, Fanatics and BetRivers side by side, with the best price for each bet highlighted. Tap any column heading to sort by it, including % difference. Tap any price to add it to the parlay calculator.
• The odds discrepancies tab lists the biggest price differences across books for every market.
• The +EV 🔎 tab does the fair-price math for every market and lists the bets where a book’s price beats it, with the edge for each.
• The EV calculator checks any single price against your own estimate of the win chance.
• The free parlay calculator shows what a parlay pays and how often it has to hit to break even.