Kalshi vs Polymarket NFL: Polymarket Cheaper on 75 of 79
One snapshot, 103 lines, three venues: how fees and market structure put different prices on the same NFL outcome.
Published 2026-10-30 · Data as of 2026-10-30 · Market & data intelligence · Educational, not advice.
On October 30, ahead of the weekend's games, Delta Arc compared 103 NFL lines on Kalshi, Polymarket and DraftKings. Each price was converted to the all-in cost of a $1 payout. Polymarket was cheapest on 64 lines and cheaper than Kalshi on 75 of the 79 lines both exchanges listed. Median gaps by market type ran from 1.2 to 1.7 cents. Fees, order books and sportsbook vig explain how the prices are built.
What the snapshot measured
At 13:51 UTC on October 30, Delta Arc's BM Dash compared 103 NFL lines across 14 upcoming games on three venues: Kalshi, Polymarket and DraftKings. Every price in it uses the same unit, which is the all-in cost for a buyer to receive a $1 payout if the outcome happens. Lower is cheaper.
That shared unit matters more than it sounds. The three venues quote prices in different formats and charge in different ways, so their headline numbers can't be compared directly. The dashboard rolls each venue's costs into one figure so the prices can be lined up side by side.
- Kalshi: the best ask (the lowest price a seller will currently accept) plus Kalshi's taker fee. At the time of the snapshot, per Kalshi's fee schedule, that fee was 0.07 × contracts × price × (1 − price), rounded up to the next cent.
- Polymarket: the price including its sports taker fee, which Polymarket's documentation set at the time at 0.05 × shares × price × (1 − price).
- DraftKings: the implied probability of the posted American odds, vig included, taken from ESPN's odds feed.
Two exchanges and a sportsbook
Kalshi and Polymarket are exchanges. Every contract has a buyer and a seller, and the exchange matches them and takes a fee. Prices are set by the traders' bids and asks, and they keep moving until the game is decided.
DraftKings is a sportsbook. It sets its own odds and holds the other side of every bet. Its margin, called the vig, is built into those odds, so the dashboard counts it as part of the cost instead of as a separate fee.
So this isn't three versions of the same thing. It is two marketplaces, where a fee sits on top of a price set by other traders, compared with a house that sets the price itself.
Where each venue came out
Of the 103 lines, Delta Arc counted Polymarket as the cheapest venue on 64, DraftKings on 24 and Kalshi on 15.
Between the two exchanges, the result was lopsided. Both listed 79 of the lines, and Polymarket was cheaper than Kalshi on 75 of them, with a median gap of 1.3 cents per $1 of payout. Against the sportsbook, Kalshi was cheaper than DraftKings for the same outcome on 28 of 65 comparable lines.
By market type, the median gap between the cheapest and most expensive venue was 1.7 cents on moneylines (28 lines), 1.3 cents on point spreads (32 lines) and 1.2 cents on totals (43 lines).
Why small gaps still matter
A cent or two per dollar sounds like rounding. It's better read as the cost of getting in. A contract pays at most $1, so a couple of cents is a real share of the most a buyer could ever receive. The buyer pays that cost on every contract, whatever the result.
How the fee formula shapes this
Both exchange fees are built on the same term, price × (1 − price). That term is largest when a contract trades near the middle and shrinks toward either end. So the fee is heaviest on evenly matched outcomes and lightest on heavy favorites and low-priced contracts. For sports takers, Kalshi's coefficient of 0.07 is higher than Polymarket's 0.05, and Kalshi also rounds up to the next cent.
That fee difference points the same way as the snapshot, but it is only one input. The other is the ask, which depends on what sellers on each exchange will accept at that moment. The snapshot reports only the all-in result. It doesn't show how much of each gap came from the fee and how much from the order book.
Lines that stood out
A few lines stood out. At 13:51 UTC on October 30, LAC to win (Los Angeles C at Los Angeles R) cost 27.6 cents on Polymarket, 29.0 on Kalshi and 31.2 on DraftKings. NYJ −7.5 (Las Vegas at New York J) cost 23.5 cents on Polymarket and 27.0 on Kalshi. SEA +5.5 (Chicago at Seattle) cost 76.5 cents on Polymarket and 80.0 on Kalshi.
Two of those three are low-priced contracts. At a low price, any gap in cents is a larger fraction of the total cost, so the structural difference between venues shows up most plainly there.
Reading the favorites
On Kalshi at 13:51 UTC on October 30, the weekend's biggest moneyline favorites included CIN to win (Tennessee at Cincinnati) at 87.0 cents all-in, JAC to win (Indianapolis at Jacksonville) at 83.0 and NE to win (New England at Miami) at 79.0. Those prices include the fee, so they should not be read directly as probabilities.
The words fee included matter. The all-in price mixes the cost of trading with what the market believes, so it sits a little above the ask on its own. The ask without the fee is the cleaner read of what the market implies. The all-in figure is what a buyer actually pays.
What this is and isn't
These are prices for a buyer at one moment. They are not a recommendation and not a forecast. Prices on both exchanges move until the games start, and being the cheapest venue at 13:51 UTC says nothing about which outcome will happen.
Delta Arc's Prediction Markets product covers Kalshi and Polymarket.
Sources: Delta Arc BM Dash; Kalshi fee schedule; Polymarket documentation; ESPN odds feed.
Sources
Outside pages cited in this post, in order of first citation
- Kalshi's fee schedulekalshi.com
- Polymarket's documentationdocs.polymarket.com
- ESPN's odds feedespn.com
This is the free read. Delta Arc Prediction Markets covers Kalshi and Polymarket. Get early access.