Figures as of Nov 4, 2026, 21:27 UTC

Polymarket vs Kalshi vs Limitless vs the sportsbooks: what a parlay costs

On a two-leg parlay of two different games, the cheapest US sportsbooks charge about 5% over their own fair price and the big retail books about 10%. A Polymarket combo costs whatever margin over fair the market maker quotes you, plus a taker fee of 0.05 x p x (1 - p) per share. Polymarket is the cheaper side when the quote is within roughly 4% of fair; today the median two-leg combo traded at +5% over fair, so it is a close race that the quote decides.

How each side prices a parlay

A sportsbook multiplies the decimal odds of the legs. It adds no separate parlay charge for legs from different games: the margin is already inside each leg and compounds, which is why a two-leg parlay holds about twice what a single bet does and a five-leg parlay far more.

Polymarket does not multiply anything. A market maker quotes one price for the whole combo, and the taker fee is 0.05 x p x (1 - p) per share. As a share of the price that is 5% x (1 - p), so it costs about 4.75% on a 5-cent longshot and 2.5% at 50 cents: the cheaper the combo, the more the fee bites.

A worked example

The falcons to win their nfl game and the st. louis cardinals to win their mlb game, priced on September 24, 2026. Polymarket had the two legs at 30.5c and 40.5c, which multiply to a fair price of 12.35c. Dividing each book's margin out of its own two prices gives a fair price of 12.77c, so the two venues agreed on the odds to within half a cent. What they charge over it differs:

A Polymarket quote 10% over fair on the same pair would be 13.59c plus 0.59c of fee, or 14.17c all in: dearer than every book except FanDuel. At 4% over fair the same combo lands at about 13.4 cents, level with the cheapest.

So which is cheaper?

• Two legs, different games: a close race. The sharp and offshore books sit around 5% over fair, the retail apps around 10%, and Polymarket is whatever you are quoted plus a fee of roughly 4% to 5% of the price on a cheap combo.
• Longer parlays: the books' margin compounds with every leg while Polymarket's fee does not, but the quotes widen too. Today's median runs +5% on two legs, +7% on three and +20% at seven or more.
• Same-game parlays: not comparable at all. Books price those with correlation models they do not publish, and a naive fair price is wrong for both venues.

What combo buyers actually pay on Polymarket

Median margin over fair, pre-game combos whose legs come from different games, last 7 days, rebuilt from Polygon:

Those are prices people paid, not quotes they were offered, and they move daily: today's numbers is the live version.

And against Limitless packs

Limitless, another prediction market, sells the same idea as a pack: a curated bundle of two to ten legs at one posted multiplier. There is no quote and no order book on them, and the house takes a stated 10% vig, which is +11% on the price.

On October 3, 2026 I priced every pack they listed, 40 of them (seven of two legs, twenty of three, thirteen of four), against those packs' own leg prices:

Limitless charges the same +11% whatever the parlay, because the vig is a flat cut of the payout. Every pack they sell, priced. Polymarket's cost grows with every leg instead, so it is the cheaper venue at two and three legs, the two meet at about four, and past that Polymarket is dearer by a widening margin. One caveat in Polymarket's favour: its column is what buyers actually paid, including the market maker's spread, while Limitless's is the posted price. One against: the dearest pack that day cost +72% over fair, well above the advertised vig, so the posted number is not a promise.

And against Kalshi

Kalshi, the other US prediction exchange, sells no parlays at all, so there is no combo price to compare. What it does give is a second opinion on each leg: ComboCheck prices your legs there too and multiplies them into a fair price that owes nothing to Polymarket's own order books. Where the two exchanges disagree on a leg, the fair price your combo is measured against is the thing in doubt, which is worth knowing before you accept any quote. That comparison runs live in the app, leg by leg, on the slip itself.

What this comparison cannot tell you

• A book that prices parlays on its own engine, rather than by multiplying its two prices, may charge more than the table above shows.
• Nothing here accounts for limits, availability in your state, bonuses, withdrawal terms or tax treatment, all of which can matter more than a cent of price.
• ComboCheck is independent and sells nothing: no book or exchange pays for a place in that table.

The comparison runs live inside the app for any two legs from different games: the result card lists each book's price for your combo next to Polymarket's. How every number is calculated.

Check your own combo quoteFree, no sign-in.