Is your Polymarket combo a fair price?
ComboCheck checks a Polymarket combo (parlay) quote against its fair price: the legs' probabilities multiplied together. It adds Polymarket's taker fee, shows how far over fair you would pay, and gives a 0 to 100 deal score against real combo trades rebuilt from the Polygon blockchain. Free, no sign-in, no wallet.
How the check works
- Pick the same legs you picked on Polymarket, or press Fetch quote and ComboCheck asks Polymarket's own gateway to price them.
- Type the price you were quoted, in cents per share.
- Read the verdict: the fair price, the taker fee, your margin over fair, and how that price compares with what other people paid for combos like it.
What a Polymarket combo costs
The fair price of a combo is its legs multiplied, which assumes they are independent. On top of the quote, Polymarket charges a taker fee of 0.05 x price x (1 - price) per share, so a 30-cent combo carries about 1.05 cents of fee. What buyers actually pay over fair, by number of legs and sport, is on today's numbers, updated through the day.
Is a Polymarket combo cheaper than Kalshi, Limitless or a sportsbook?
ComboCheck prices the same bet in four places, so you can tell. The cheapest US sportsbooks charge about 5% over their own fair price on a two-leg parlay and the big retail apps about 10%. Limitless sells parlays as packs at a flat 10% vig, about 11% over fair whatever the parlay. Kalshi sells no parlay, so it serves as a second opinion on each leg. A Polymarket combo undercuts all of them on two or three legs and gets dearer from four up. The live figures are in what a parlay costs on Polymarket, Kalshi, Limitless and the sportsbooks.
Is ComboCheck free, and is it run by Polymarket?
It is free, needs no account and never asks for a wallet, a private key or funds. It is independent and not run by or affiliated with Polymarket, and it places no bets: it only reads public data. Links to Polymarket carry ComboCheck's referral code, as do links to Limitless, at no cost to you.
Where the numbers come from
Leg probabilities are the midpoints of Polymarket's own order books. Completed combo trades are decoded from Polygon, which is what the deal score compares your price with. Full details are in the methodology, and the same data is free to use through the API and MCP server.
Read more
- Polymarket parlay calculator: how it works, with a worked example
- Today's numbers: what combo buyers pay over fair, by number of legs and sport
- FAQ: are Polymarket combos a good deal, how they are priced, what fee they carry
- Polymarket vs Kalshi vs Limitless vs sportsbooks: the same bet priced in four places
- How it works: where the data comes from and how every number is calculated
- Contact: a combo that priced oddly, or a market we are missing