How to read Polymarket odds
In short
On Polymarket a share of an outcome costs between 1¢ and 99¢ and pays $1 if it happens, so the price in cents is the market's chance in percent. A candidate at 45¢ has about a 45% chance; buying at 45¢ pays about 2.2x if right.
Price, chance and payout
Price in cents equals chance in percent. Payout multiple equals 100 divided by the price: 45¢ pays about 2.2x, 20¢ pays 5x, 5¢ pays 20x.
Multi-outcome markets (who wins an election, what price Bitcoin hits) list one Yes price per outcome. The leader is the highest price, and the prices add up to roughly 100%.
Moves, volume and liquidity
The 24-hour move is how many points the price changed since yesterday. Volume is how much has traded; liquidity is how much sits in the order book. A big move on low volume means less than the same move on heavy trading.
The spread
You buy at the ask and sell at the bid. On busy markets they are 1¢ apart; on thin ones the gap is wider, and the midpoint is a better read of the chance than the last trade.