Kalshi vs Polymarket NFL: Polymarket Lower on 82 of 86
A Friday snapshot of 108 NFL lines shows the same outcome carrying three different prices.
Published 2026-11-06 · Data as of 2026-11-06 · Market & data intelligence · Educational, not advice.
Before this weekend's NFL games, Delta Arc compared 108 lines on Kalshi, Polymarket and DraftKings, using the all-in cost of a $1 payout. In the 2026-11-06 snapshot, Polymarket was the lowest-priced venue on 70 lines, DraftKings on 26 and Kalshi on 12. The typical gap was one to two cents. The post sets out how each venue's fees and vig work. These are buyer prices at one moment, not forecasts or picks.
What was compared, and how
At 13:55 UTC on 2026-11-06, Delta Arc's BM Dash took a snapshot of 108 NFL lines across 15 upcoming games, priced on Kalshi, Polymarket and DraftKings. Every figure in this post comes from that one moment. None of it is a live reading, and prices may have changed since.
The comparison uses one unit throughout: the all-in cost for a buyer of a contract that pays $1 if the outcome happens. Lower is cheaper. For Kalshi, that means the best ask plus Kalshi's taker fee. Putting everything in the same unit is the only fair way to compare an exchange with a sportsbook, because the two charge for access in very different ways.
Two exchanges and a sportsbook
Kalshi and Polymarket are exchanges. Every contract has a buyer and a seller. The exchange matches them and takes a fee, but it never takes the other side itself. The price a buyer pays is the best ask, the lowest price any seller is currently offering, and it keeps moving right up until the outcome is known.
DraftKings is a sportsbook. It sets its own odds and holds the other side of every wager. Its margin, called the vig, is built into the odds rather than charged as a separate line item. In this comparison, DraftKings prices are the implied probability of the posted American odds with the vig included, taken from the Delta Arc BM Dash snapshot. That turns a sportsbook quote into the same cost of a $1 payout as everything else.
How the exchange fees work
Per Kalshi's fee schedule, the taker fee is 0.07 × contracts × price × (1 − price), rounded up to the next cent. Per Polymarket's documentation, sports takers pay 0.05 × shares × price × (1 − price). The Polymarket prices here include that fee.
Both formulas have the same shape. The price × (1 − price) term is largest when a contract trades near 50 cents and shrinks as the price moves toward zero or a dollar. So fees weigh most on close contests and least on lopsided ones. The two formulas differ in their multiplier, 0.07 against 0.05, and Kalshi's round-up to the next cent can count for more on small orders.
What the board showed
Out of 108 lines in the Delta Arc snapshot of 2026-11-06, Polymarket was the lowest-priced venue on 70, DraftKings on 26 and Kalshi on 12.
Looking only at the two exchanges in that 13:55 UTC snapshot, 86 lines were priced on both. Polymarket was cheaper than Kalshi on 82 of them, and the median gap was 1.3 cents per $1 of payout. Kalshi against DraftKings was more even: Kalshi was cheaper for the same outcome on 31 of 72 comparable lines.
By market type, the median gap between the cheapest and dearest venue in the snapshot was:
- Moneylines: 1.8 cents per $1 of payout, across 30 lines
- Point spreads: 1.3 cents, across 35 lines
- Totals: 1.3 cents, across 43 lines
Where the spread between venues was widest (13:55 UTC snapshot, 2026-11-06)
- Over 50.5, Detroit at Miami: Polymarket 49.8 cents, Kalshi 51.0 cents, DraftKings 53.5 cents.
- KC to win, New York J at Kansas City: Polymarket 81.5 cents, Kalshi 83.0 cents, DraftKings 85.2 cents.
- PHI to win, New York G at Philadelphia: Polymarket 38.7 cents, Kalshi 41.0 cents, DraftKings 42.4 cents.
In all three, the same $1 outcome had three different prices, and the order was the same each time. The structure covered above can contribute to that order: a lower fee multiplier lowers the all-in price, and a sportsbook's vig raises it. But the multiplier difference alone moves the price by roughly half a cent at most, before Kalshi's round-up, so fees do not by themselves account for gaps of this size. Order book depth at the moment of the snapshot also matters, because the best ask is only as good as whoever happens to be offering it. This post does not break down how much each factor contributed.
Reading an all-in price as a probability
A contract's price can be read as an implied probability. Delta Arc's 2026-11-06 snapshot listed some of the weekend's highest-priced moneyline contracts on Kalshi:
- KC to win (New York J at Kansas City): 83.0 cents all-in, about an 83% implied chance including the fee
- SF to win (Las Vegas at San Francisco): 82.0 cents all-in, about 82%
- SEA to win (Arizona at Seattle): 80.0 cents all-in, about 80%
Notice the words "including the fee." An all-in price mixes two things: the market's estimate of the outcome and the cost of getting access to it. That is why the same game can imply slightly different probabilities on different venues. The outcome is the same, but the cost of reaching it isn't. Before treating any single venue's price as the crowd's forecast, ask how much of that number is the fee or the vig.
What this snapshot is not
These are prices for a buyer at one moment, not a recommendation. A lower price doesn't say anything about whether an outcome will happen, and this post doesn't suggest taking any side.
Exchange prices move continuously before kickoff as injury news, weather and order flow come in. A snapshot is a photograph of that process. To see Kalshi and Polymarket markets side by side, see Delta Arc's Prediction Markets product.
Sources: Delta Arc BM Dash, Kalshi fee schedule, Polymarket documentation.
Sources
Outside pages cited in this post, in order of first citation
- Kalshi's fee schedulekalshi.com
- Polymarket's documentationdocs.polymarket.com
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