Polymarket, Kalshi, Novig or ProphetX: Which Prediction Market Is Really the Cheapest Place to Bet on Sports?

Polymarket, Kalshi, Novig or ProphetX: Which Prediction Market Is Really the Cheapest Place to Bet on Sports? Sponsored

Prediction markets have become the standard answer to "where should I bet on sports?" in crypto circles. The pitch is simple: no bookmaker in the middle, so no bookmaker's cut. A report by WagerBeasts, a sports betting analytics website that tracks odds at more than 60 sportsbooks, exchanges and prediction markets, tested that pitch against real prices. The answer depends on which prediction market you use.

WagerBeasts took the last price each site offered in the hour before kickoff on 488 games across eight sports, played between 18 and 23 September 2026: 8,746 prices from 59 betting sites. Four of those sites are prediction markets that list sports: Kalshi, Polymarket, Novig and ProphetX. On the price you see, all four were cheaper than the big sportsbooks. Once the fees were added, they were not all cheap.

Key takeaways

• Prediction markets build the smallest fee into their odds, about 1% on a typical game, against 5.2% at regulated US sportsbooks.
• The price on screen is not always the price you pay. Kalshi adds a fee on top when you buy. Polymarket and ProphetX already include theirs. Novig charges nothing on pre-game bets.
• All in, a $100 bet at even money costs about $0.95 at Novig, $1.60 at ProphetX, $3.15 at Polymarket and $4.30 at Kalshi. A regulated US sportsbook costs about $4.90.
• After fees, Novig had the best odds on 54% of the outcomes it priced. Kalshi fell from 34% to 9%.
• On one NFL game, the best place to back the favorite was a prediction market, and the best place to back the underdog was a sportsbook.

Two fees, not one

Every set of odds has a fee built in. Turn the odds for each outcome into a percentage and add them up: if the total comes to 105%, the site keeps about $5 of every $100 bet on that game. On that measure, prediction markets are the cheapest sites in the study by a distance. The typical prediction-market price carried about 1%, offshore books 3.7%, regulated US sportsbooks 5.2% and regulated UK, European and Australian sportsbooks 6.1%.

The catch is the second fee, the one some prediction markets charge on top of the price. Each of the four handles it differently:

Typical values across the 488 games. For comparison, the same $100 bet costs about $3.10 at Pinnacle, $4.90 at a regulated US sportsbook and $5.75 at a regulated UK, European or Australian one.

Kalshi is the case that surprises people. Its odds carry almost no fee, and on screen it had the best price on 34% of the outcomes it listed, neck and neck with Novig. Its trading fee is charged when you buy, though, and after it Kalshi costs about what the big US sportsbook apps cost. Polymarket works the other way round. Its odds look a little more expensive because its fee is already inside them, and it moved up the rankings once the other sites' fees were counted.

One NFL Sunday, four prediction markets

On Sunday 20 September, the Carolina Panthers visited the Atlanta Falcons. In the last hour before kickoff, 47 of the betting sites WagerBeasts tracks had a price on the game, including all four prediction markets. The market made Carolina a 56% favorite. They won 34-3. WagerBeasts runs the same comparison for every game of the week on its NFL predictions page.

Here is what $100 returned at a cross-section of those sites, with every fee counted:

Returns include the $100 stake. Kalshi is shown after its trading fee and Betfair Exchange after its 5% commission on winnings. Polymarket's and ProphetX's prices already include their fees. Highest return in each column in bold.

Three things stand out in that one game.

First, a prediction market was the best place to back the favorite. Polymarket returned $182 on the Panthers, $16 more than bet365 on the same bet.

Second, Kalshi went from competitive to last among the four. Its price on screen would have returned about $179, level with ProphetX. After its fee, $173.

Third, the best price on the underdog came from a sportsbook. bet365 paid $225 on the Falcons, and Hard Rock Bet and TAB matched it. Sportsbooks do not always spread their fee evenly across a game: on this one, bet365 took almost all of its cut from Panthers backers and almost none from Falcons backers.

The full study shows the same pattern at scale. After fees, Novig had the best odds on 54% of the outcomes it priced, Pinnacle on 20% (mostly underdogs), Polymarket on 19%, ProphetX on 15% and Kalshi on 9%. On favorites, Novig had the best odds 37% of the time and Pinnacle only 5.7%.

The cheapest price is not always available

Two limits apply to every prediction market that do not apply to a sportsbook. The best price on an order book is only good for as much money as someone has offered at it, which is not always your stake. And whether you can use a given market at all depends on where you live. Kalshi, Polymarket, Novig and ProphetX each have their own rules on who can trade sports.

Prediction-market prices also move more. Between a day before kickoff and the start of the game, WagerBeasts measured prediction-market prices moving about 2.7 percentage points on average, against 1.6 to 1.8 at regulated and offshore sportsbooks. A market run by a smaller group of traders swings more than a bookmaker's trading desk, even when it ends up in the same place.

Do the traders know more than the bookmakers?

Not in this data. On 1,206 outcomes that a prediction market and the sportsbooks both priced, the typical gap between the prediction market's probability and the sportsbook average was under one percentage point, with no lean either way. WagerBeasts also checked which type of site predicted results best, and none beat the sportsbook average by any margin the data could detect. With a prediction market you pay less for the same forecast. You are not buying a better one.

How to use this

• Compare the price after fees, not the price on screen. This matters most on Kalshi, where the fee is added at checkout.
• Check every game. The cheapest site changes from game to game, as the Falcons–Panthers game shows. Across the study, the best available odds paid about 5.1% more than the middle sportsbook on the same bet, and 4.4% more after fees.
• Favorites and underdogs can have different best sites. Across the study, Novig had the best odds most often on favorites. On underdogs, Pinnacle was often best too.