How Oddy works: where the odds come from and how often they update
Oddy puts every regulated US sportsbook next to the prediction markets Kalshi and Polymarket for the same bet, with the exchange prices stated after their fees. This page says where each price comes from and how fresh it is. The prices on Oddy right now were taken Nov 4, 1:11 AM ET.
Kalshi and Polymarket, every 5 seconds during live games
Odds data feeds carry Kalshi and Polymarket prices too, on the feed’s own schedule. Oddy reads Kalshi and Polymarket US directly from their own public APIs instead: every 5 minutes before a game, and every 5 seconds once it starts. The page in your browser asks for new live prices every 5 seconds too, so a live exchange price on screen is usually under 15 seconds old. A market that closes or has nothing left to buy drops off instead of showing a stale price.
Update speed by source
| Prices | Pre-game | Live |
|---|---|---|
| Kalshi Its own public API | 5 minutes | 5 seconds |
| Polymarket US Its own public API | 5 minutes | 5 seconds |
| 10 sportsbooks A licensed odds data feed | 5 minutes | 20 seconds |
| Novig and ProphetX A licensed odds data feed | 5 minutes | 20 seconds |
| Live scores A public scoreboard | — | 5 seconds |
| Kalshi futures Its own public API | 10 minutes | — |
| Sportsbook futures A licensed odds data feed | Twice a day | — |
Exchange prices are shown after fees
Kalshi and Polymarket quote a price in cents and charge a trading fee on top of it. A 50¢ Kalshi contract is not even money: after Kalshi’s fee it pays like a -107 bet. Oddy converts every exchange price to the American odds you receive once the fee is paid, using each exchange’s published fee schedule (last checked October 2026), so an exchange and a sportsbook on the same row mean the same thing: what the bet pays. The Kalshi fee calculator shows the math for any price.
Which books you see
The regulated US sportsbooks (DraftKings, FanDuel, BetMGM, Caesars, BetRivers, theScore Bet, Fanatics, Hard Rock Bet, Bally Bet and betPARX), the CFTC-regulated exchanges Kalshi and Polymarket US, and, in the states with no sportsbook, the CFTC-licensed exchanges Novig and ProphetX. Offshore books are left out on purpose. Pick your state and the books you cannot use there are hidden, and the best price is recomputed from the ones you can. Odds by state lists what is legal where.
Measured, every week
Every game Oddy covers is captured once before it starts, and the weekly Kalshi and Polymarket report counts how often each exchange beat every sportsbook on the moneyline, after fees. When a game ends its page keeps the closing prices and the final score at the same address.
What Oddy does not do
Oddy takes no bets, holds no money and sells no picks. There is no account. Prices move, so always confirm at the book before you bet.
Questions about Oddy’s data
How often does Oddy update Kalshi and Polymarket odds?
Every 5 seconds while a game is live, read straight from Kalshi’s and Polymarket US’s own public APIs rather than through an odds aggregator. Before a game starts, every 5 minutes. A live exchange price on screen is usually under 15 seconds old.
Are Kalshi and Polymarket prices on Oddy before or after fees?
After. Each exchange charges a trading fee on top of its price (Kalshi 0.07 × price × (1 − price) a contract, Polymarket US 0.0695), so Oddy converts every exchange price to the American odds you actually receive once the fee is paid. That is the number that can be compared with a sportsbook, whose odds already include its margin.
Where do the sportsbook odds come from?
A licensed odds data feed covering the regulated US books: DraftKings, FanDuel, BetMGM, Caesars, BetRivers, theScore Bet, Fanatics, Hard Rock Bet, Bally Bet and betPARX. Offshore books are left out on purpose.
Does Oddy take bets or sell picks?
No. Oddy shows prices and links to the book with the best one. It takes no bets, holds no money and sells no picks.