GUIDE · UPDATED 2026-10-17
How to Read Prediction Market Odds: Cents Are Probability
Prediction market "odds" are the easiest odds in finance to read: the price is the probability. A YES contract at $0.63 implies a 63% chance. That's the whole conversion — but a few habits separate people who quote prices from people who actually understand them.
The conversions worth memorizing
| YES price | Implied probability | Decimal odds | American odds | Read it as |
|---|---|---|---|---|
| $0.10 | 10% | 10.0 | +900 | unlikely |
| $0.33 | 33% | ~3.0 | ~+200 | underdog |
| $0.50 | 50% | 2.0 | +100 | coin flip |
| $0.63 | 63% | ~1.6 | ~−170 | moderate favorite |
| $0.90 | 90% | ~1.1 | ~−900 | near-lock (but not) |
To convert: decimal odds = 1 ÷ price. American odds: for prices above 50¢ it's −100 × P/(1−P); below 50¢ it's +100 × (1−P)/P — where P is the probability as a decimal.
YES + NO = $1.00 — the most useful identity
Because one side pays $1.00 and the other $0.00, the NO price is always (100 − YES)¢. Seeing YES at 63¢ tells you NO costs 37¢. If a market's YES and NO quotes ever sum to more than $1.00 plus fees, there's an arbitrage — which is exactly why it almost never happens on liquid venues.
What the price is NOT telling you
- Thin markets lie politely. A 2¢-wide market with $400 of volume can sit at a "wrong" price because nobody has paid to fix it. Check volume and spread before trusting any quote — especially long-tail markets.
- News reprices contracts instantly. A 90% favorite can gap to 60% on one report. The price is a live estimate, not a settled fact.
- The rule defines the bet. "Will the candidate win?" can hinge on withdrawal timing, recounts or runoff rules. Read the resolution source before you trade on a cheap contract that looks "obviously" wrong.
- Fees bend the edge. A 1.75¢ taker fee on a 50¢ contract is a 3.5% hurdle; on a 5¢ longshot contract the same fee is 35% of your stake. Fee-aware traders favor mid-range prices for small edges — see how fees are calculated.
A 30-second sanity check before any trade
- Price → probability in your head (63¢ = 63%).
- Spread × your size → is the round-trip cost small against your edge?
- Resolution rule → does "win" mean what you think it means?
- Volume → are there enough other traders for this price to mean something?
Master those four and every platform — Polymarket, Kalshi or a brokerage app — reads the same way. For where each venue fits best, see the 2026 ranking.
Is 99¢ a guaranteed win?
No. Contracts at 99¢ lose 1% of the time — and when they lose, you lose your whole stake. "Near-lock" is a probability, not a promise.Why is my fill worse than the price I saw?
You crossed the spread, and your size ate through multiple price levels. The quoted price was for the resting size at the touch — anything beyond fills deeper in the book.Do odds differ between prediction markets and sportsbooks?
Often, yes — books add margin and manage liability, while exchanges drift with trader flow. The gaps are why arbitrage between the two exists, and why the same game can show different probabilities on each venue.Educational content only — not financial advice. Prices shown are illustrative examples, not live quotes. Verified October 2026.
We compared regulation, fees, custody and market breadth across the big four.