How to Calculate Odds
What is Odds?
An odds calculator converts between different probability formats: decimal odds (European), fractional odds (UK), moneyline/American odds (US), and implied probability. Each format expresses the same underlying probability differently.
Step-by-Step Guide
- 1Decimal odds = 1 / probability (includes stake: 2.50 means $1 returns $2.50 total)
- 2Fractional odds (e.g. 3/2): profit/stake = 1.5× profit on $1 bet
- 3American odds: +150 means $100 bet wins $150; −150 means bet $150 to win $100
- 4Implied probability = 1/decimal odds = stake/(stake+profit) for fractional
Worked Examples
Input
Decimal odds 2.50
Result
40% implied probability, +150 American, 3/2 fractional
1/2.50 = 0.40 = 40%
Input
American odds −200
Result
66.7% implied probability, decimal 1.50
Heavy favorite
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