Prediction Markets vs. Sports Betting

Prediction markets vs. sports betting: the quick answer

On a prediction market you trade contracts with other people on a federally regulated exchange, and the price is the market's chance: a contract at 62¢ pays $1 if it happens, so the market gives it 62%. At a sportsbook you bet against the house at odds it sets, with its margin (the vig) built in, under a state gaming license.

That one difference drives the rest: who sets the price, what it costs you, whether you can get out early, whether you get limited for winning, and where each is legal. The live table above shows today's busiest sports markets priced both ways, and what $100 really returns on each.

Prediction markets vs. sportsbooks, side by side

Fees and availability change; our prediction market fees page and legal tracker keep both current.

How a prediction market prices a game

Every game on Kalshi or Polymarket US is a pair of contracts, one per team, each paying $1 if that team wins. If the favorite trades at 73¢, the market gives it a 73% chance, and $100 buys 136 contracts that pay $136 if it wins. The underdog's contract trades near 27¢ to 29¢: the two sides add up to a little over $1, and that gap is the spread between buyers and sellers, not a house margin.

Prices move every time someone trades, so they react to injuries, weather and the game itself in seconds. You can see each venue's price for every game on our NFL odds and NBA odds pages, and every sport on sports prediction markets today.

How sportsbook odds work

US sportsbooks quote American odds. A minus number is what you risk to win $100 (−160: risk $160 to win $100); a plus number is what $100 wins (+135: $100 wins $135). Turned into chances, −160 is 61.5% and +135 is 42.6%. Those add up to 104.1%, not 100%: the extra 4.1% is the vig, the book's built-in margin.

The classic case is a −110 line on both sides of a spread. Each side implies 52.4%, together 104.8%, so the book keeps about 4.5% of what's bet no matter who wins. On parlays, futures and long shots the margin is usually far larger.

Fees vs. the vig: what each really costs

A prediction market's cost is a visible fee. Kalshi charges 7% × price × (1 − price) per contract, rounded up to the cent: about 1.75¢ on a contract at 50¢, less as the price moves toward 0¢ or $1. On $100 at a 50¢ price that is $1.75, or 1.75%, and you see it before you trade.

A sportsbook's cost is hidden in the odds. You never see a fee line, but you get paid less than the true chance would pay: about 4.5% less on a standard line. The "real cost of $100" box above runs both on today's busiest game, with live prices.

Two caveats. Exchange prices include a spread between the best bid and ask, which can be wide on quiet markets. And sportsbooks run promotions (odds boosts, bonus bets) that can beat an exchange on a given bet; prediction markets have sign-up bonuses too.

Are prediction markets gambling?

Legally, they are regulated as financial contracts: event contracts on exchanges registered with the Commodity Futures Trading Commission, the same regulator as futures markets. That federal status is why Kalshi and Polymarket US operate in states where sportsbooks are not legal.

Several states and tribes disagree, arguing that sports contracts are sports betting under another name, and courts have split on it. The outcome of those cases decides where sports contracts stay available; our legal tracker follows every ruling.

For you as a user the practical differences are the structure: you trade with other people rather than the house, you can sell before the game ends, and winning doesn't get your account limited. Money is at risk either way.

Which is more accurate, prediction markets or sportsbooks?

On big games both are sharp. A busy prediction market and a sportsbook's closing line usually land within a point or two of each other, because both are pushed by informed money. Prediction markets show you the crowd's chance directly and update with every trade; a sportsbook's line moves when the book chooses to move it.

The gaps appear on thinner markets: lightly traded props, futures far from settlement, smaller sports. There, an exchange price can be stale and a book's line can carry a large margin. Comparing the two is often where the value is.

Do people make money on prediction markets?

Some do; most don't. There is no house edge working against you, but fees and spreads still cost something, and you're trading against people who may know more. Analyses of exchange trading consistently find that a small share of accounts earn most of the profits.

What helps: knowing a sport or league deeply, comparing prices across venues before you trade (our odds pages show the lowest price to buy on each), and selling early when a price moves your way rather than always holding to the end.

When to use each

• Use a prediction market if you want to see the market's chance directly, pay a visible fee instead of a margin, sell before the game ends, trade where sportsbooks aren't legal, or trade beyond sports (elections, the Fed, crypto).
• Use a sportsbook if you want same-game parlays, the deepest prop menus, live-betting features and promotions, and sports betting is legal where you live.
• Use both to compare prices: the same game can be cheaper on one side of the fence, especially on favorites, where a sportsbook's margin bites hardest.

Taxes apply to winnings either way; our prediction market tax guide covers how they're reported.

Prediction market sign-up offers

Each app's current new-user bonus, checked by our editors. Bonuses are trading credit; read each app's terms before you sign up.