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Odds converter
Convert decimal, fractional and American odds into implied probability and Kalshi/Polymarket cents — with the formulas and examples behind each conversion.
Odds converter
One price, five formats. See what it means for your stake.
Enter odds greater than 1, e.g. 2.50.
Use the currency selected alongside.
Instant calculation
- Implied probability
- 40.00%
- Decimal odds
- 2.500
- Fractional odds ≈
- 3/2
- American odds
- +150
- Contract price, before fees
- 40.00¢
- Potential return
- US$25.00
- Potential profit
- US$15.00
Implied probability reflects the price, including any bookmaker margin. It is not a prediction. Return includes your stake; profit excludes it. Rounded equivalents may differ slightly.
Calculated on your device. No sign-up.
Five ways to read a price
Fractional odds
UK and IrelandThe numerator is the profit for a stake equal to the denominator. Odds of 5/2 return a £10 stake plus £25 profit. Decimal odds = 1 + numerator ÷ denominator. Evens (1/1) equals decimal 2.00.
Decimal odds
Europe, Australia, CanadaThe total return per unit staked, including your stake. Odds of 2.50 mean a $10 bet returns $25 ($15 profit). The implied probability is simply 1 ÷ decimal.
American odds
United StatesA positive number (+150) is the profit on a $100 stake. A negative number (-200) is the stake needed to make a $100 profit. Favourites are negative, underdogs positive.
Implied probability
EverywhereThe probability implied by the odds, expressed as a percentage. It is the common ground between every format — convert to probability first, then to anything else.
Cents (Kalshi / Polymarket)
Prediction marketsOn prediction markets the price of a contract in cents is the market's implied probability. A contract trading at 65¢ means a 65% implied chance, and pays out $1 (100¢) if it resolves yes.
How to convert odds
Every format converts through implied probability. Convert your odds to a probability first, then out to any other format.
Fractional → decimal
decimal = 1 + numerator ÷ denominatorOdds of 5/2 → 1 + 5 ÷ 2 = 3.50.
Decimal → implied probability
probability = 1 ÷ decimalOdds of 2.50 → 1 ÷ 2.50 = 0.40 = 40%.
Implied probability → decimal
decimal = 1 ÷ probabilityA 40% implied probability → 1 ÷ 0.40 = 2.50.
American (positive) → probability
probability = 100 ÷ (odds + 100)+150 → 100 ÷ 250 = 0.40 = 40%.
American (negative) → probability
probability = |odds| ÷ (|odds| + 100)-200 → 200 ÷ 300 = 0.667 = 66.7%.
Cents → decimal
decimal = 100 ÷ centsA contract at 65¢ → 100 ÷ 65 = 1.54.
Quick reference table
| Cents | Decimal | American | Implied probability |
|---|---|---|---|
| 10¢ | 10.00 | +900 | 10% |
| 20¢ | 5.00 | +400 | 20% |
| 25¢ | 4.00 | +300 | 25% |
| 33¢ | 3.03 | +203 | 33% |
| 40¢ | 2.50 | +150 | 40% |
| 50¢ | 2.00 | -100 | 50% |
| 60¢ | 1.67 | -150 | 60% |
| 67¢ | 1.49 | -203 | 67% |
| 75¢ | 1.33 | -300 | 75% |
| 80¢ | 1.25 | -400 | 80% |
| 90¢ | 1.11 | -900 | 90% |
💡 On Polymarket and Kalshi, the price in cents equals the market's implied probability. A contract at 65¢ = 65% implied probability.
Frequently asked questions
How do I convert fractional odds?
Divide the numerator by the denominator and add 1. For 5/2, decimal odds are 1 + 5 ÷ 2 = 3.50. Evens, or 1/1, equals 2.00. The converter accepts fractions and the word evens.
What are decimal odds?
Decimal odds show the total amount returned per unit staked, stake included. At odds of 2.50 a winning $10 bet returns $25. The implied probability is 1 divided by the decimal odds, so 2.50 equals a 40% implied chance.
How do I convert American odds to probability?
For positive American odds, probability = 100 ÷ (odds + 100); +150 implies a 40% probability. For negative odds, probability = |odds| ÷ (|odds| + 100); -200 implies a 66.7% probability.
What does a price in cents mean on Polymarket or Kalshi?
On prediction markets the price of a contract in cents equals its implied probability. A Yes contract trading at 65¢ reflects a 65% implied probability and pays out $1 if the outcome resolves Yes. Fees are excluded.
What is implied probability and why does it matter?
Implied probability is the chance of an outcome that a set of odds corresponds to. Comparing the bookmaker's implied probability with your own estimate is how you spot a value bet — a bet where the odds are higher than the true probability justifies.