What Is a Prediction Market?
A prediction market lets you buy yes or no on a real event: a team winning, a total going over. The price, in cents, is the market's estimate of the chance it happens.
What an event contract is
Every market is a yes/no question, and every contract settles one of two ways: $1 if the answer is yes, $0 if it is no. Prices run from 1¢ to 99¢, and other traders set them, not a bookmaker.
100 contracts cost $65 and pay $100 if it happens.
The price is a probability
A 65¢ price means the market makes it a 65% chance. That is the same number a sportsbook hides inside its odds, shown plainly. The "no" side of the same question trades near the rest of the dollar: about 35¢ here. Buy prices on the two sides add up to a dollar or a little more; that gap is what you pay to trade right now.
Cents to American odds
To compare a contract with a sportsbook price, turn the cents into odds. It is the implied probability formula run backwards.
Under 50¢ (an underdog)((100 − cents) ÷ cents) × 100. At 40¢: 60 ÷ 40 × 100 = +150.
Exactly 50¢Even money, +100.
So a 55¢ contract is −122, and a 40¢ contract pays like a +150 underdog.
The fee changes the price
A sportsbook builds its margin into the odds. An exchange charges a fee instead, and the fee is part of your price. Kalshi publishes its taker fee (the fee on an order that fills right away) as a formula:
You pay $65 + $1.60 = $66.60 for a $100 payout. Your real price is 66.6¢: a 66.6% break-even, or about −199 instead of −186.
The fee is biggest at 50¢ ($1.75 per 100 contracts) and shrinks toward 1¢ and 99¢. Fee schedules are set by each exchange and can change, so check the current one before you trade.
Prediction markets vs sportsbooks
| Sportsbook | Prediction market | |
|---|---|---|
| Who sets the price | The book | Other traders |
| How the price is shown | American odds (−186) | Cents (65¢) |
| What it costs you | A margin built into the odds | A fee on the trade |
| What a win pays | The odds you took | $1 a contract |
Kalshi is a US exchange, regulated by the CFTC, where you trade on the outcome of real events: sports, economics, politics and more. Polymarket US, Novig and ProphetX are the other prediction markets on our odds screen. Who can sign up, and where, differs from one to the next and from the sportsbooks: each app checks your age and location when you join.
Comparing them on the odds screen
The odds screen puts Kalshi, Polymarket US, Novig and ProphetX in their own group to the right of the sportsbooks. Each price shows as the exchange shows it, in American odds: a 55¢ contract is −122. The Best odds column counts the taker fee before it crowns an exchange, so an exchange is never best at a price its fee would take away. At 55¢, Kalshi's fee makes that −122 about −131.
- Kalshi, new accounts: trade $25, get $55 with code MCBETS. New Kalshi accounts only · 18+ · Kalshi terms apply. Claim $55 on Kalshi →
- Polymarket: free to join. Join the MC Polymarket squad →
Trading involves risk: you can lose the money you trade. MC Sports HQ is a referral partner and may be paid when you sign up. We don't take trades or bets.
- A contract pays $1 if it happens and $0 if it doesn't; the price in cents is the market's chance.
- 65¢ is about −186; 40¢ is +150.
- Count the fee: 100 contracts at 65¢ on Kalshi really cost 66.6¢ each.
Put it to work
The MC Sports model boards rank every player and game, every game day, and show the numbers behind each score.
See the model boards →