Prediction Markets vs Sportsbooks

Do Prediction Markets Beat Sportsbooks on Price?

Usually, but not all of them, and the exception matters. Across 28,023 moneylines from 484 games in the last 30 days where all five venues quoted the same side, Polymarket US held the best price 78.3% of the time. Kalshi finished last of the five at 3.2%, once its per-contract taker fee is added and its quotes are read as executable asks. "Exchange" is not a synonym for "better price": you still have to check.

1. Polymarket US 78.3%
2. Pinnacle 10.2%
3. FanDuel 7.2%
4. DraftKings 6.8%
5. Kalshi 3.2%

Matched lines only: a market counts only when every venue above quoted that same side, so nobody is credited for the games they skipped. Measured September 8, 2026 and recomputed as the scanner runs. How this is calculated.

Why Only 30 Days, and Why Only These Five?

Matched lines is computed from the per-book snapshot record, which is kept on a rolling 90-day window and queried here in windows up to 30 days. The all-time view on Book Comparison reaches further back but is coverage-confounded: it credits a venue for beating whoever happened to quote a game, which rewards quoting few markets. The honest instrument cannot be all-time and the all-time instrument cannot be honest, so we publish both and say which is which.

ProphetX and Novig are left out of the ranking above on purpose, and the reason is sample size rather than anything about the venues. Both are quoted on far fewer games than Kalshi and Polymarket US, so putting them in a five-way matched comparison would shrink it to the handful of markets all five priced at once, and report a precision we do not have. Their prices are still on the board and still counted everywhere a best price is chosen. Read more on how ProphetX's no-vig pricing works.

Where Does Kalshi Actually Stand?

Kalshi's structural pitch is real: it is an exchange, so there is no vig baked into the line. What changed is the measurement. A pricing fix in July 2026 corrected our Kalshi quotes to the price a taker can actually execute rather than a bid-side fallback, and on corrected numbers Kalshi no longer leads. The full detail, including the earlier number and why it was wrong, is in our Kalshi versus sportsbooks analysis.

How Much Should You Trust an Exchange Price?

Enough to check it, and not enough to skip asking how it was built. An exchange quote is only worth the offer sitting underneath it, and this site got that wrong on its own board: the published account is the exchange price autopsy, which found 19 percent of quoted exchange prop sides were derived from the opposite side of the order book rather than read from a real offer. Every exchange price in the comparison above is the price a $100 order actually fills at, walked down the book, with the venue's fee already applied. On the sportsbook side of the same question, a 30-day study of the whole board found that how far a book sits from the market and whether it is repeatably wrong are close to unrelated, at r = +0.03.