Passing Yards o124.5
Kalshi
-669 vs
Hardrock
-2500
+9.16%
edge
Why the price is different
Same outcome, two business models.
A sportsbook sets a price and builds its margin into both sides — that margin is the vig, and it is the reason a coin flip is priced at -110 instead of +100. A prediction market does something different: Kalshi, Polymarket and Novig match one trader against another and charge a fee on the trade, so the quote you see is closer to what the market actually believes.
That difference is worth money on the props you were already betting. BeatVig converts every quote — book and exchange — to implied probability, removes the vig from both, and flags the ones where the exchange is the cheaper side of the same outcome.
Live examples right now
Straight off the board, no cherry-picking.
Passing Yards o149.5
Kalshi
-567 vs
Hardrock
-1600
+9.11%
edge
Passing Yards o174.5
Kalshi
-614 vs
Hardrock
-1400
+7.34%
edge
Passing Yards o149.5
Kalshi
-614 vs
Hardrock
-1400
+7.34%
edge
Passing Yards o174.5
Kalshi
-317 vs
Hardrock
-500
+7.31%
edge
Strikeouts o3.5
Kalshi
+257 vs
Hardrock
+185
+7.08%
edge
The three venues, by sport
How each one charges you, and where it prices which sport.
- Kalshi
- Kalshi is a CFTC-regulated exchange. Every contract settles at $1 or $0, so a 42¢ quote is a 42% implied probability with no sportsbook margin layered on top.
- Kalshi charges a per-contract trading fee instead of building a margin into the line. The fee is a curve, not a flat rake: it peaks at roughly 1.75¢ on a contract priced near 50¢ and shrinks toward zero at both extremes, and maker fees are a quarter of taker fees.
- Polymarket
- Polymarket is an order-book market: the price is whatever two traders agree on, and a share that settles at $1 quotes as a probability directly.
- Polymarket's taker fee is a fraction of a percent, which makes its headline quote very close to the all-in cost and often the cheapest of the exchanges in the middle of the price range.
- Novig
- Novig is a peer-to-peer exchange wearing a sportsbook interface: your price comes from another user rather than from a trading desk that sets a margin.
- Novig takes a small per-contract fee from the taker and pays makers a rebate rather than baking vig into the line. It is low-fee rather than fee-free, and when Novig steps in as counterparty in a thin market a spread comes back into the price.
- ProphetX
- ProphetX is a betting exchange: users post the prices and you take the other side of someone else's bet instead of accepting a desk's number.
- ProphetX charges commission on net winnings rather than embedding a margin, so the cost is explicit and only applies when you win.
Head to head, live
Which venue is currently the cheaper side.
Prediction markets vs sportsbooks — FAQ
Do prediction markets have lower vig than sportsbooks?
Usually, because a prediction market charges a fee alongside the price instead of building a margin into it, so the quote you see is close to the implied probability itself. The saving is real but it is not automatic, and on some markets a sportsbook is still the better number.
How do Kalshi's fees compare to sportsbook juice?
Kalshi charges a per-contract trading fee rather than a flat cut of winnings, and the fee is a curve that peaks at roughly 1.75 cents on a contract priced near 50 cents and shrinks toward zero at both extremes. A sportsbook's margin is inside the price instead, so you pay it on every bet whether it wins or loses.
Can I bet player props on Kalshi or Polymarket?
Kalshi lists player markets as "X or more" yes/no contracts rather than as over/under lines, and Polymarket's player-prop coverage is still filling in. BeatVig converts each contract to the equivalent over price so it can be compared to a sportsbook number directly.
How do you compare a prediction market price to a sportsbook price?
Convert both to the implied probability of the same outcome, then remove the sportsbook's vig so the two numbers mean the same thing. The cheaper venue is the one implying the lower probability for the side you want.
Are prediction markets legal in the US?
Kalshi and Polymarket US both operate through CFTC-regulated exchanges rather than under state sports-betting licences, which is why their footprint differs from a sportsbook's. Availability still varies by venue and by state, so check the venue before assuming you can trade there.
Start with a market
The props people actually shop for.