On Kalshi and Polymarket, prices are quoted in cents from 1 to 99. The number isn't arbitrary: a contract at 65¢ means the market prices the event at a 65% chance. The price is the implied probability — which makes converting it to American or decimal odds straightforward.
The one rule
A contract settles at $1 if the event happens and $0 if it doesn't. So the price you pay is what the market thinks the event is worth — i.e., its probability. Price in cents = implied probability percent.
- 65¢ → 65% implied
- 50¢ → 50% — a true coin flip
- 8¢ → 8% — a longshot
- 92¢ → 92% — a heavy favorite
Converting to decimal odds
Decimal odds = 100 ÷ price. It's the total return per $1 risked.
- 65¢ → 100 / 65 = 1.54
- 50¢ → 100 / 50 = 2.00
- 25¢ → 100 / 25 = 4.00
Decimal is the easiest bridge — once you have it, every other format follows.
Converting to American odds
American odds split at 50¢. Above 50¢ the side is a favorite (negative number); below 50¢ it's an underdog (positive number).
- Above 50¢ (favorite): American = −(price / (100 − price)) × 100. So 65¢ → −(65/35)×100 = −186.
- Below 50¢ (underdog): American = ((100 − price) / price) × 100. So 35¢ → ((65)/35)×100 = +186.
- 50¢: exactly +100 (even money).
Don't want to do this by hand? The prediction market odds converter turns any cents price into implied %, American, decimal, and fractional instantly.
YES and NO are two sides of the same price
Every market has a YES side and a NO side, and they sum to about 100¢. If YES is 65¢, NO is 35¢. Buying NO at 35¢ is the same as betting the event won't happen — you collect $1 if it doesn't. The tiny amount the two sides sum above 100¢ (the bid-ask spread), plus the venue's trading fee, is the cost of doing business — analogous to a sportsbook's hold, but typically much smaller.
Why this is cleaner than a sportsbook line
On a sportsbook, a −110 line implies about 52.4% — but both sides of a market add up to more than 100%, and the excess is the vig baked into the price. To find the real probability you have to strip the vig out.
A prediction market price skips that step: the cents figure is already the market's probability estimate. That directness is a big part of why traders who care about true probability gravitate to these markets. For how the cost models differ overall, see prediction markets vs sportsbooks.