Bookmakers Odds Calculator

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bookmakers odds calculator
Decimal Odds (e.g., 2.50)Fractional Odds (e.g., 6/4)American Odds (e.g., +150)Implied Probability (%)
Results:
Decimal: –
Fractional: –
American: –
Probability: –
Potential Profit: $–
Total Payout: $–
function gcd(a, b){return b ? gcd(b, a % b) : a;}function calculateOdds(){var type = document.getElementById('odds_type').value;var valStr = document.getElementById('odds_val').value;var stake = parseFloat(document.getElementById('stake_val').value);var stepsDiv = document.getElementById('steps_output');var decimalOdds = 0;var stepsHtml = "Conversion Steps:
";if(!valStr || isNaN(stake)){alert('Please enter valid odds and stake');return;}if(type === 'decimal'){decimalOdds = parseFloat(valStr);stepsHtml += "1. Decimal odds entered: " + decimalOdds;}else if(type === 'fractional'){if(valStr.indexOf('/') === -1){decimalOdds = parseFloat(valStr) + 1;}else{var parts = valStr.split('/');var num = parseFloat(parts[0]);var den = parseFloat(parts[1]);decimalOdds = (num / den) + 1;stepsHtml += "1. Fractional " + num + "/" + den + " to Decimal: (" + num + "/" + den + ") + 1 = " + decimalOdds.toFixed(3);}}else if(type === 'american'){var amer = parseFloat(valStr);if(amer > 0){decimalOdds = (amer / 100) + 1;stepsHtml += "1. Positive American to Decimal: (" + amer + " / 100) + 1 = " + decimalOdds.toFixed(3);}else{decimalOdds = (100 / Math.abs(amer)) + 1;stepsHtml += "1. Negative American to Decimal: (100 / " + Math.abs(amer) + ") + 1 = " + decimalOdds.toFixed(3);}}else if(type === 'probability'){var prob = parseFloat(valStr);decimalOdds = 100 / prob;stepsHtml += "1. Probability to Decimal: 100 / " + prob + "% = " + decimalOdds.toFixed(3);}if(decimalOdds = 2){outAmer = "+" + Math.round((decimalOdds – 1) * 100);}else{outAmer = "-" + Math.round(100 / (decimalOdds – 1));}var a = Math.round((decimalOdds – 1) * 1000);var b = 1000;var common = gcd(a, b);var outFrac = (a / common) + "/" + (b / common);var profit = stake * (decimalOdds – 1);var payout = stake * decimalOdds;document.getElementById('res_dec').innerHTML = decimalOdds.toFixed(3);document.getElementById('res_frac').innerHTML = outFrac;document.getElementById('res_amer').innerHTML = outAmer;document.getElementById('res_prob').innerHTML = outProb.toFixed(2) + "%";document.getElementById('res_profit').innerHTML = profit.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});document.getElementById('res_payout').innerHTML = payout.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});if(document.getElementById('show_steps').checked){stepsDiv.innerHTML = stepsHtml + "
2. Profit: Stake (" + stake + ") × (Decimal Odds – 1) = " + profit.toFixed(2);stepsDiv.style.display = 'block';}else{stepsDiv.style.display = 'none';}}

Using the Bookmakers Odds Calculator

Whether you are a casual sports fan or a seasoned bettor, understanding how to read and convert betting lines is essential. Our bookmakers odds calculator is designed to handle all major betting formats simultaneously. By entering a single value, you can instantly see the equivalent price in other formats and determine exactly how much a winning bet will return.

This tool is particularly useful for comparing prices across different sportsbooks that may use different default formats (such as UK bookies using fractions and US bookies using American money lines).

Odds Format
Choose between Decimal (2.00), Fractional (1/1), American (+100), or Implied Probability (50%).
Odds Value
The numerical price offered by the bookmaker for a specific event.
Stake
The amount of money you intend to wager. The calculator uses this to project profit and payout.

How It Works: The Mathematics of Betting

Bookmakers use odds to represent the likelihood of an outcome, but they also build in a profit margin (the "vig" or "overround"). To master betting, you must understand the conversion formulas used by the bookmakers odds calculator:

Decimal Odds to Others

Decimal odds are the most straightforward. They represent the total payout (stake + profit) for every $1 wagered.

  • To Probability: (1 / Decimal Odds) * 100
  • To Fractional: (Decimal Odds – 1) expressed as a fraction.
  • To American (if 2.0 or higher): (Decimal Odds – 1) * 100
  • To American (if less than 2.0): -100 / (Decimal Odds – 1)

Calculation Example

Example: You want to bet $50 on a team with American odds of -150. You want to know the implied probability and the potential profit.

Step-by-step solution:

  1. Input Odds Type: American
  2. Input Odds Value: -150
  3. Input Stake: 50
  4. Step 1: Convert to Decimal
    Formula for negative American odds: (100 / 150) + 1 = 0.666 + 1 = 1.667
  5. Step 2: Calculate Profit
    Profit = Stake * (Decimal – 1) = 50 * (1.667 – 1) = 50 * 0.667 = $33.35
  6. Step 3: Calculate Implied Probability
    Prob = (1 / 1.667) * 100 = 60%

Common Questions

What is implied probability?

Implied probability is the conversion of bookmaker odds into a percentage. It represents the likelihood the bookmaker expects the outcome to happen. If your calculated probability for an event is higher than the bookmaker's implied probability, you have found a "value bet."

Why do the probabilities of all outcomes add up to more than 100%?

This is known as the "bookmaker's overround" or the "juice." Because bookmakers want to make a profit regardless of the outcome, they set the odds so that the combined probability of all possible results (e.g., Home Win, Draw, Away Win) is typically between 102% and 110%. The extra percentage is their margin.

What is the difference between profit and payout?

The profit is the net gain from your bet (your winnings), while the payout is the total amount returned to you by the bookmaker, which includes your original stake plus your profit.

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