Odds converter
Type odds in any format — American, decimal, fractional, a probability, or a prediction-market contract price — and read the rest.
| American | Decimal | Implied | Prediction-market price |
|---|---|---|---|
| -500 | 1.200 | 83.3% | 83.3¢ |
| -300 | 1.333 | 75.0% | 75.0¢ |
| -200 | 1.500 | 66.7% | 66.7¢ |
| -150 | 1.667 | 60.0% | 60.0¢ |
| -110 | 1.909 | 52.4% | 52.4¢ |
| +100 | 2.000 | 50.0% | 50.0¢ |
| +120 | 2.200 | 45.5% | 45.5¢ |
| +150 | 2.500 | 40.0% | 40.0¢ |
| +200 | 3.000 | 33.3% | 33.3¢ |
| +300 | 4.000 | 25.0% | 25.0¢ |
| +500 | 6.000 | 16.7% | 16.7¢ |
Why the contract price column
Kalshi and Polymarket contracts trade between 0 and $1 and pay $1 if the event happens, so the price is the probability. A sportsbook moneyline of −163 and a 62¢ contract are the same price in different clothes — which is exactly the comparison that finds sportsbook↔prediction-market arbitrage. The converter shows both so you can line them up by eye.
Frequently asked questions
How do you convert American odds to probability?
For a negative number: |odds| / (|odds| + 100). −150 → 150 / 250 = 60%. For a positive number: 100 / (odds + 100). +150 → 100 / 250 = 40%. The probability is also the price of the equivalent prediction-market contract in cents.
How do you convert decimal odds to American?
If decimal ≥ 2.00: American = (decimal − 1) × 100. If decimal < 2.00: American = −100 / (decimal − 1). So 2.50 → +150 and 1.667 → −150.
What is the sportsbook equivalent of a 62¢ contract?
A 62¢ YES contract implies 62%, which is decimal 1.613 or American −163. That is how ArbMonster's sportsbook↔prediction-market engine compares a moneyline to a 'team wins' contract.
Related: American odds explained · Implied probability · Vig calculator · Kalshi vs Polymarket prices
Educational tool. Verify every price on the venue before acting; nothing here is financial or betting advice.