Convert a Polymarket price to odds
A Polymarket price is the cost of one share that pays $1 if it wins. Type the price and the amount. The calculator shows the odds before and after the fee, the share of bets you need to win to break even, and what the fee is on your amount.
| Odds before the fee | 2.000 |
| Odds after the fee | 1.951 |
| American odds after the fee | −105 |
| Win this share of bets to break even | 51.25% |
| Shares you get | 200 |
| Fee on this amount | $2.50 |
| Paid in total | $102.50 |
| Paid out if it wins | $200.00 |
How the numbers are worked out
- Odds before the fee: 1 ÷ price. At 50¢ that is 1 ÷ 0.50 = 2.000.
- The fee: rate × shares × price × (1 − price). On a sports market, 200 shares at 50¢ pay 0.05 × 200 × 0.50 × 0.50 = $2.50. The fee is paid on top of the price, and you get all your shares.
- Odds after the fee: one share costs price × (1 + rate × (1 − price)). At 50¢ on sports that is $0.5125, so the odds are 1 ÷ 0.5125 = 1.951.
- Break-even: the same $0.5125 as a share of $1. You need to win 51.25% of such bets to come out even.
A limit order that waits for its price pays no fee, so its odds are the same as before the fee. It may never trade, and on sports markets open orders are cancelled when the game starts. A winning share pays $1 with nothing taken out; the fee was paid when you bought. More in does Polymarket take a cut of winnings.
Three prices on a sports market
| Price | Odds before | Odds after fee | Break-even |
|---|---|---|---|
| 20¢ | 5.000 | 4.808 | 20.80% |
| 50¢ | 2.000 | 1.951 | 51.25% |
| 80¢ | 1.250 | 1.238 | 80.80% |
The fee moves cheap shares furthest from their price. How this compares with a sportsbook's margin is in Polymarket vs a sportsbook.
Your own fees, added up
The calculator shows one bet. Polymarket shows the fee on each trade but never a total, and the profit on your profile already has the fees taken out. Type your Polymarket @name or paste your profile address into the free check above to see every fee you paid in the last 30 days, to the cent.
Questions
How do I convert Polymarket prices to odds?
Divide 1 by the price in dollars. 20¢ is 5.000, 50¢ is 2.000 and 80¢ is 1.250 in decimal odds. If you buy at once on a sports market, add the fee first: one share costs price × (1 + 0.05 × (1 − price)), so 50¢ becomes $0.5125 and the odds become 1.951.
What do Polymarket prices mean?
A price is the cost of one share that pays $1 if its side wins and $0 if it loses. A price of 65¢ means traders put the chance of that side at about 65%.
How do I get American odds from a Polymarket price?
First get decimal odds: 1 ÷ price, or 1 ÷ the cost with the fee. If the decimal odds are 2.00 or more, American odds are +(decimal − 1) × 100. If they are under 2.00, American odds are −100 ÷ (decimal − 1). At 50¢ with the sports fee, 1.951 becomes −105.
What win rate do I need to break even on Polymarket?
The cost of one share with the fee, as a share of $1. On a sports market that is 20.80% at 20¢, 51.25% at 50¢ and 80.80% at 80¢ when you buy at once. A limit order that waits for its price breaks even at the price itself.