Odds on Calculator

Use this calculator to convert between different betting odds formats (Fractional, Decimal, Moneyline) and understand the implied probability of an outcome. "Odds on" typically refers to a favorite where the potential winnings are less than the stake.

Select Odds Format: Fractional Odds Decimal Odds Moneyline Odds

Enter Odds Value:

Results:

Implied Probability:

Decimal Odds:

Fractional Odds:

Moneyline Odds:

Understanding Odds On Betting

"Odds on" refers to a betting scenario where the potential winnings are less than the amount staked. This typically indicates a strong favorite, meaning the bookmaker believes the event has a high probability of occurring. For example, if you bet on an event at 1/2 (one-to-two) odds, you would win $1 for every $2 staked. This is in contrast to "odds against," where winnings exceed the stake (e.g., 2/1 odds).

Different Odds Formats

Betting odds are presented in various formats, each conveying the same information about probability and potential payout:

Fractional Odds (e.g., 1/2, 5/4, 2/1): Popular in the UK and Ireland. The first number (numerator) represents the potential profit, and the second number (denominator) represents the stake required to win that profit. For "odds on" bets, the numerator is smaller than the denominator (e.g., 1/2).
Decimal Odds (e.g., 1.50, 2.25, 3.00): Common in Europe, Canada, and Australia. This format represents the total return for every $1 staked, including your original stake. So, 1.50 odds means a $1 stake returns $1.50 (a $0.50 profit). For "odds on" bets, the decimal odds will be between 1.00 and 2.00 (exclusive of 2.00).
Moneyline Odds (e.g., -200, +125): Predominant in the United States.
- Negative Moneyline (e.g., -200): Indicates the amount you need to stake to win $100. This is used for favorites ("odds on" scenarios). So, -200 means you must bet $200 to win $100 profit.
- Positive Moneyline (e.g., +125): Indicates the amount you would win for a $100 stake. This is used for underdogs.

Implied Probability

Implied probability is the bookmaker's assessment of the likelihood of an event occurring, derived directly from the odds they offer. It's calculated differently for each odds format but always represents the percentage chance. For example, 1/2 odds imply a 66.67% chance, while -200 moneyline odds also imply 66.67%.

It's important to note that implied probabilities from bookmakers often sum to more than 100% across all outcomes in an event. This difference is known as the "overround" or "vig" (vigorish), which is how bookmakers ensure a profit margin.

How to Use the Calculator

Select Odds Format: Choose whether you are entering Fractional, Decimal, or Moneyline odds.
Enter Odds Value: Input the specific odds. For fractional, use the "X/Y" format (e.g., 1/2). For moneyline, include the sign (e.g., -200 or +150).
Calculate: Click the "Calculate Odds" button to see the conversions to other formats and the implied probability.

Examples of Odds On Calculations

Fractional Odds: 1/2
- Implied Probability: 2 / (1 + 2) = 0.6667 = 66.67%
- Decimal Odds: (1 / 2) + 1 = 1.50
- Moneyline Odds: -100 / (1 / 2) = -200
Decimal Odds: 1.50
- Implied Probability: 1 / 1.50 = 0.6667 = 66.67%
- Fractional Odds: (1.50 – 1) / 1 = 0.5/1, simplified to 1/2
- Moneyline Odds: -100 / (1.50 – 1) = -200
Moneyline Odds: -200
- Implied Probability: |-200| / (|-200| + 100) = 200 / 300 = 0.6667 = 66.67%
- Decimal Odds: (100 / |-200|) + 1 = 1.50
- Fractional Odds: 100 / |-200| = 1/2

These examples demonstrate how different odds formats represent the same underlying probability for an "odds on" favorite.

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