Sportsbooks vs Prediction Markets: Where Should You Trade?

Two systems, same math

Sportsbooks and prediction markets both let you bet on outcomes. But the mechanics are fundamentally different, and understanding those differences is how you find edge.

Sportsbooks set the lines. You're betting against the house at prices they choose. Odds are expressed as American (-110), decimal (1.91), or fractional (10/11). The book bakes its margin into both sides.

Prediction markets use order books. You're trading contracts priced between $0.01 and $0.99, where the price represents implied probability. You're betting against other traders, not the house.

Use the odds converter to translate between formats, or the prediction market converter to go from contract prices to odds.

Fee structures

This is where the platforms diverge most.

A sportsbook charging -110/-110 has a 4.8% hold built into the odds. You never see a separate "fee" — it's baked in. The true probability of a 50/50 event is 50%, but you're paying as if it's 52.4%.

Prediction markets charge differently. Polymarket has zero explicit fees but earns on the spread. Kalshi charges fees on winning trades — typically 5-10% of profit. On a $100 bet that returns $180, Kalshi takes $4-8 of your $80 profit.

Run the numbers on any trade with the prediction market fee calculator. The effective cost varies wildly depending on the contract price.

Liquidity and execution

Sportsbooks offer instant execution at posted odds. You click, you're filled. Limits vary by sport and bettor profile, but the price is the price.

Prediction markets have visible order books. You can see depth at every price level. But thin markets mean slippage — placing a $5,000 order on a contract with $500 of liquidity at your price means you're moving the market against yourself.

Market types

Sportsbooks cover traditional sports with deep, efficient lines. Spreads, totals, props, futures — thousands of markets per event.

Prediction markets cover politics, economics, weather, culture, and current events. Election odds, Fed rate decisions, whether a bill passes Congress. These markets have no sportsbook equivalent.

When to use each

Use sportsbooks when: you're betting traditional sports, need instant fills, or want established market depth.

Use prediction markets when: you're trading non-sports events, want to exit positions before settlement, or find pricing inefficiencies in thinner markets.

Use both when: the same event is priced on both platforms. That's where cross-platform arbitrage lives — and where the real edge is.

For a head-to-head on the two biggest prediction markets, see Polymarket vs Kalshi.