Bookies Odds Calculator

Use this calculator to convert between different odds formats, calculate implied probability, and determine potential payouts for your bets.

Your Stake: Odds Value: Odds Format: Decimal (e.g., 2.5) Fractional (e.g., 5/2) American (e.g., +150 or -150)

Results

Implied Probability:

Potential Payout:

Potential Profit:

Odds Conversions

Decimal Odds:

Fractional Odds:

American Odds:

Understanding Bookies Odds

Bookies odds are a fundamental part of sports betting, representing the likelihood of an event occurring and determining the potential payout for a winning bet. They are presented in various formats, each with its own way of expressing the same underlying probability.

What Do Odds Represent?

At their core, odds reflect the bookmaker's assessment of the probability of a particular outcome. However, it's important to remember that these odds also include the bookmaker's margin (known as "vig" or "overround"), which ensures they make a profit regardless of the outcome.

Common Odds Formats

There are three primary formats for displaying betting odds:

1. Decimal Odds

Decimal odds are perhaps the easiest to understand for calculating potential returns. They represent the total return for every unit staked, including your original stake. For example, odds of 2.50 mean that for every $1 you bet, you will receive $2.50 back if your bet wins (which includes your original $1 stake, so your profit is $1.50).

Calculation: Payout = Stake × Decimal Odds
Implied Probability: (1 / Decimal Odds) × 100%

2. Fractional Odds

Commonly used in the UK and Ireland, fractional odds (e.g., 5/2, 10/1) represent the profit you will receive relative to your stake. The first number (numerator) is the profit, and the second number (denominator) is the stake required to win that profit. For example, 5/2 odds mean you win $5 profit for every $2 you stake. Your total return would be your $2 stake plus the $5 profit, totaling $7.

Calculation: Payout = Stake × ((Numerator / Denominator) + 1)
Implied Probability: (Denominator / (Numerator + Denominator)) × 100%

3. American Odds (Moneyline Odds)

Prevalent in the United States, American odds are displayed with a plus (+) or minus (-) sign. They indicate either how much you need to bet to win $100 (for negative odds) or how much you win for every $100 staked (for positive odds).

Positive Odds (e.g., +150): You win $150 profit for every $100 staked.
Negative Odds (e.g., -200): You need to stake $200 to win $100 profit.
Calculation (Positive): Payout = Stake × ((American Odds / 100) + 1)
Calculation (Negative): Payout = Stake × ((100 / |American Odds|) + 1)
Implied Probability (Positive): (100 / (American Odds + 100)) × 100%
Implied Probability (Negative): (|American Odds| / (|American Odds| + 100)) × 100%

What is Implied Probability?

Implied probability is the percentage chance of an outcome occurring, as suggested by the betting odds. It's calculated by converting the odds into a percentage. For instance, decimal odds of 2.00 imply a 50% chance (1/2.00). Understanding implied probability helps you assess whether you believe the bookmaker's odds offer value – if you think an event has a higher chance of happening than the implied probability, it might be a good bet.

How to Use This Calculator

Enter Your Stake: Input the amount of money you wish to bet.
Enter Odds Value: Type in the odds provided by the bookmaker.
Select Odds Format: Choose whether your odds are in Decimal, Fractional, or American format.
Click "Calculate Odds": The calculator will instantly display the implied probability, your potential payout, and profit, along with conversions to the other two odds formats.

Examples:

Let's say you want to bet $50.

Decimal Odds (e.g., 2.50):
- Implied Probability: (1 / 2.50) = 0.40 = 40%
- Potential Payout: $50 × 2.50 = $125.00
- Potential Profit: $125.00 – $50 = $75.00
Fractional Odds (e.g., 5/2):
- Implied Probability: (2 / (5 + 2)) = 2/7 ≈ 0.2857 = 28.57%
- Potential Payout: $50 × ((5 / 2) + 1) = $50 × (2.5 + 1) = $50 × 3.5 = $175.00
- Potential Profit: $50 × (5 / 2) = $50 × 2.5 = $125.00
American Odds (e.g., +150):
- Implied Probability: (100 / (150 + 100)) = 100 / 250 = 0.40 = 40%
- Potential Payout: $50 × ((150 / 100) + 1) = $50 × (1.5 + 1) = $50 × 2.5 = $125.00
- Potential Profit: $50 × (150 / 100) = $50 × 1.5 = $75.00
American Odds (e.g., -200):
- Implied Probability: (200 / (200 + 100)) = 200 / 300 ≈ 0.6667 = 66.67%
- Potential Payout: $50 × ((100 / 200) + 1) = $50 × (0.5 + 1) = $50 × 1.5 = $75.00
- Potential Profit: $50 × (100 / 200) = $50 × 0.5 = $25.00

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Please check the odds value and format."); return; } // — Display main results — document.getElementById("impliedProbabilityResult").innerHTML = impliedProbability.toFixed(2) + "%"; document.getElementById("potentialPayoutResult").innerHTML = "$" + potentialPayout.toFixed(2); document.getElementById("potentialProfitResult").innerHTML = "$" + potentialProfit.toFixed(2); // — Convert Decimal Odds to other formats for display — document.getElementById("decimalOddsResult").innerHTML = decimalOdds.toFixed(2); // Fractional conversion var fractionalOddsString = ""; if (decimalOdds > 1) { var profitRatio = decimalOdds – 1; // This is the X/Y part // Try to find a common denominator for simple fractions var tolerance = 0.001; // For floating point comparisons var foundFraction = false; for (var d = 1; d <= 100; d++) { // Check denominators up to 100 var n = profitRatio * d; if (Math.abs(n – Math.round(n)) < tolerance) { fractionalOddsString = Math.round(n) + "/" + d; foundFraction = true; break; } } if (!foundFraction) { // Fallback for complex fractions or if no simple one found // Convert to a fraction with 100 as denominator and simplify var num = (profitRatio * 100).toFixed(0); var den = 100; var gcd = function(a, b) { return b ? gcd(b, a % b) : a; }; var commonDivisor = gcd(parseInt(num), den); fractionalOddsString = (parseInt(num) / commonDivisor) + "/" + (den / commonDivisor); } } else if (decimalOdds === 1) { fractionalOddsString = "0/1 (Even Money)"; } else { fractionalOddsString = "N/A (Odds = 2) { // Positive American odds americanOddsString = "+" + ((decimalOdds – 1) * 100).toFixed(0); } else if (decimalOdds > 1 && decimalOdds < 2) { // Negative American odds americanOddsString = "-" + (100 / (decimalOdds – 1)).toFixed(0); } else if (decimalOdds === 1) { americanOddsString = "Even Money (0)"; } else { americanOddsString = "N/A (Odds < 1)"; // Should not happen with valid input } document.getElementById("americanOddsResult").innerHTML = americanOddsString; } // Initial call to set placeholder on load window.onload = updateOddsPlaceholder;