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How to read Polymarket sports odds
Arbs research desk · Updated 2026-11-01 · Reviewed 2026-11-01 · 3 min read
The short answer: A Polymarket share pays $1 if its outcome happens. Its price in cents is the market’s implied probability, so a 62¢ share is a 62% chance, decimal odds of 1.61, or −163 in American odds.
Shares, not tickets
A sportsbook takes your stake and pays out at fixed odds. Polymarket is an exchange: you buy shares of an outcome from other traders. Each share settles at $1 if the outcome happens and $0 if it does not.
Because the payout is always $1, the price is the probability the market assigns. Buying 100 shares at 40¢ costs $40 and returns $100 if you are right, a $60 profit, the same as a +150 bet.
Every game has one share per outcome. In a two-way market the two prices add up to about $1, since exactly one side pays. If they add up to noticeably more, you are looking at the asks; if less, at the bids.
Converting cents to odds
Start from the probability p, which is the price in cents divided by 100. Decimal odds are the payout per $1 staked, stake included:
p = price in cents ÷ 100, and d = 1 ÷ p
American odds use two formulas: a positive number is the profit on a $100 stake, a negative number is the stake needed to win $100.
A = 100 × (d − 1) when d is 2 or more; otherwise A = −100 ÷ (d − 1)
Going the other way, from a sportsbook line to a Polymarket-style price:
p = 100 ÷ (A + 100) for positive A; p = −A ÷ (−A + 100) for negative A
Worked example: A 62¢ share
- p = 62 ÷ 100 = 0.62
- d = 1 ÷ 0.62 = 1.613
- d is under 2, so A = −100 ÷ 0.613 = −163
62¢ is a 62% chance, 1.61 in decimal and −163 in American odds.
The Polymarket odds converter does every format at once.
Quick reference
| Price | Probability | Decimal | American | American after taker fee |
|---|---|---|---|---|
| 10¢ | 10% | 10.00 | +900 | +857 |
| 25¢ | 25% | 4.00 | +300 | +286 |
| 40¢ | 40% | 2.50 | +150 | +143 |
| 50¢ | 50% | 2.00 | +100 | −105 |
| 60¢ | 60% | 1.67 | −150 | −158 |
| 75¢ | 75% | 1.33 | −300 | −316 |
| 90¢ | 90% | 1.11 | −900 | −947 |
Bid, ask and the price you pay
The headline price is usually the midpoint or the last trade. To buy now you pay the ask; to sell now you get the bid. On liquid NFL and NBA games the spread is often a cent; on smaller markets it can be several.
If the bid is 61¢ and the ask is 63¢, the board may show 62¢, but a market buy pays 63¢. That cent is a cost just like a book’s vig, so compare the ask, not the midpoint, with any fair price.
Depth matters for larger orders. A buy walks up the book until it is filled:
Worked example: Buying 6,000 shares
- Asks: 2,000 shares at 62¢, 3,000 at 63¢, 5,000 at 64¢
- Fill: 2,000 × 62¢ + 3,000 × 63¢ + 1,000 × 64¢ = $3,770
- Average: $3,770 ÷ 6,000 = 62.83¢
The average price is almost a cent above the best ask.
How the fee changes your real odds
Taker orders pay a fee on top of the price. With rate r it is, per share:
fee per share = r × p × (1 − p)
At 50¢ that is 1.25¢, so a 50¢ share costs 51.25¢ and the real odds are −105, not even money. The fee guide covers when you pay it and how to avoid it.
Selling before the end
Shares trade until the market closes, so you can lock a gain or cut a loss by selling at the bid. Selling into the bid is a taker order too.
Worked example: Selling a winner early
- Bought 100 shares at 40¢: $40 + $1.20 fee = $41.20
- The bid rises to 55¢. Selling 100 shares: $55 − $1.24 fee = $53.76
- Profit: $53.76 − $41.20
$12.56 locked in, whatever happens in the game.
Is the price right?
A market price is a crowd estimate, and crowds can be slow on injuries, lineups and late money. Arbs prices every game with its own model and shows that probability next to the Polymarket price on the board. When the model is above the price, the share is cheap by the model’s number.
Try it: Polymarket odds converter
Frequently asked questions
What does 70¢ mean on Polymarket?
The market gives the outcome a 70% chance. That is decimal odds of 1.43 and American odds of about −233.
How much do I win on Polymarket?
Each share pays $1 if you are right. Profit per share is $1 minus the price you paid, minus any taker fee.
Can I sell before the game ends?
Yes. Shares trade until the market closes, so you can sell at the current bid to lock a gain or cut a loss.
Why do the two sides add up to more than $1?
You are looking at the asks, which sit above the midpoint by half the spread on each side. The midpoints add up to about $1.