Prediction markets vs sportsbooks: the vig gap explained

Both a sportsbook wager and a prediction market contract let you put money on a future outcome. The economics underneath are very different — and once you understand the vigorish gap, it's hard to look at a standard −110 line the same way again.

The one number that changes everything: vigorish

Vigorish — the "vig", "juice" or "margin" — is what a sportsbook charges to accept your bet. On a canonical NFL point spread quoted at −110 on both sides, a bettor risks $110 to win $100. If the book takes equal action on each team, it collects $220 and pays out $210, keeping $10 no matter which team covers. That $10 on $220 of exposure is roughly a 4.55% hold on every matched dollar.

That's the best-case sportsbook number. On props, futures, parlays and less-liquid markets the vig routinely runs 6–10% or higher. Multi-leg parlays compound the margin on every leg, which is why the industry loves them.

A regulated US prediction market like Kalshi charges a per-contract trading fee that in practice sits well under 2% of notional, and often under 1% on higher-priced contracts. There is no "juice" priced into the quote itself — Yes and No prices must sum to $1, so the market's implied probability is the price you actually pay.

What the vig gap costs you over time

Imagine you place 200 bets of $100 each over a year at even money, and you win exactly half. On a sportsbook at −110, you risk $22,000 to bet $20,000 of notional, and you finish down roughly $1,000 purely from vig — with a perfectly break-even prediction record. On a prediction market with a 1% effective fee, the same 200 trades cost you about $200. That's an 80% reduction in structural drag before you factor in a single skill-based edge.

Use our Market Edge Calculator to see how a small change in effective cost per trade rewrites your long-run expected value.

Price discovery: order book vs. line-setter

A sportsbook line is set by a trader (or a model) and then moved to balance the book's exposure — not to reflect the market's best guess at the true probability. That's why sharp bettors talk about "beating the closing line": the closing line is a curated number, not a market-clearing price.

A prediction market is a continuous order book. Anyone can post a bid or offer; anyone can hit or lift the quote. Prices move because someone with capital disagreed enough to trade. The result is a live probability estimate that reflects real money on both sides — which is why forecasters, journalists and policy shops increasingly cite prediction market prices instead of polls.

Cash-out, hedging and getting out of a position

On a sportsbook, if you want to exit a bet early, you take the book's cash-out offer — a unilateral price with an extra margin baked in on top of the original vig. It's convenient; it's rarely fair.

On a prediction market you exit the same way you entered: by placing a market or limit order against the book. If a contract you bought at 41 cents is now trading at 62 cents, you can sell into the bid and lock the profit in real time. This makes hedging, dollar-cost-averaging and staged position sizing genuinely practical.

Regulation, funds and counterparty risk

US prediction markets in this comparison are CFTC-regulated Designated Contract Markets. Customer funds sit in segregated accounts, contracts are cash-settled against verifiable outcomes, and the exchange is subject to federal oversight of market integrity. US sportsbooks are licensed state-by-state under gaming regulators, with rules that vary substantially by state — including what markets are offered and how disputes are handled.

Offshore sportsbooks and offshore prediction markets (including Polymarket for US residents) sit outside this framework entirely and carry meaningful counterparty and legal risk.

Where sportsbooks still win

• Live in-play betting on individual plays and micro-events, where prediction markets have thinner books.
• Same-game parlays and heavily-boosted promos as a marketing hook — occasionally +EV if you shop them carefully.
• Breadth of sports coverage: every game, every league, every prop.

For everything else — elections, macro data, geopolitical events, culture, crypto, and increasingly the largest sporting events — a regulated prediction market gives you tighter pricing, more honest probabilities and materially lower structural cost.

How to try this yourself

• Read our ranking of the best US prediction market platforms to pick where to open an account.
• Compare a live line to the market's implied probability with the Implied Probability Calculator.
• Estimate payout and break-even with the Profit Calculator.
• Check your state's current legal status before depositing funds.