Head to head
Which venue is currently the cheaper side of the same player props, de-vigged and counted live.
Right now BeatVig prices 1,226 player props at both. Kalshi is the cheaper side 48% of the time (595 of 1,226), and Polymarket is cheaper on 176. This is the board as it stands at 31 Oct 12:27 ET, not an average over any period — BeatVig measures live prices and keeps no price history.
Two exchanges, no sportsbook margin on either side, and a real difference in how they charge. Kalshi's fee is a curve that peaks on near-even markets; Polymarket's is a flat fraction of a percent, which tends to make it cheaper in the middle of the price range. Kalshi lists more sports markets and carries deeper coverage; Polymarket's depth is concentrated on the games people are trading. Where both price the same prop, the number below is which one is currently ahead.
Counted above: every prop Kalshi prices lower than Polymarket. Listed below: the ones that also beat a de-vigged fair price, which is the stricter test and the only one worth acting on.
Kalshi
+15040%40¢
vs
Polymarket
+14441%41¢
· +0.98pp vs Polymarket
fair 42.5% · Bovada, multiplicative devig
+2.48pp
was the raw edge before Kalshi's
fee, which takes 2.0 percentage points of it
Kalshi
-12755.9%56¢
vs
Polymarket
-14459%59¢
· +3.07pp vs Polymarket
fair 58.4% · Bovada, multiplicative devig
+2.4pp
was the raw edge before Kalshi's
fee, which takes 2.0 percentage points of it
Kalshi
+16338%38¢
vs
Polymarket
+15639.1%39¢
· +1.04pp vs Polymarket
fair 40.2% · edge +0.19pp (worst case -3.15pp) — this edge is 0.19 percentage points under the de-vigging method BeatVig publishes and as little as -3.15 under the least flattering of the 4 methods that fit Kalshi's own two-sided prices
+2.19pp
was the raw edge before Kalshi's
fee, which takes 2.0 percentage points of it
Free accounts see a 3-edge sample from below the top of the board. Premium unlocks every prop where Kalshi beats Polymarket, in every sport.
Go PremiumAcross the 1226 player props priced at both venues right now, Kalshi is the cheaper side on 595 and Polymarket is cheaper on 176; the rest are priced identically at both. Neither venue is cheaper on everything, and this is a live count of the current boards rather than an average over time.
Every quote from both venues is converted to the implied probability of the same outcome, so a contract price and an American price become the same unit. The cheaper venue is the one implying the lower probability for the side you want.
Kalshi charges a per-contract trading fee instead of building a margin into the line. The fee is a curve, not a flat rake: it peaks at roughly 1.75¢ on a contract priced near 50¢ and shrinks toward zero at both extremes, and maker fees are a quarter of taker fees.
Polymarket's taker fee is a fraction of a percent, which makes its headline quote very close to the all-in cost and often the cheapest of the exchanges in the middle of the price range.
It is computed from the live board every time the page loads, so it reflects the prices both venues are showing at that moment rather than a snapshot taken on an earlier day.
