Odds Converter
Convert between fractional, decimal, American, implied probability, and Hong Kong odds formats.
Reviewed for accuracy by Daniel Agrici, Founder & Lead Developer
Odds Converter
Calculator
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Formula: Implied Probability = (1 / Decimal Odds) x 100
Worked example — Decimal: 3.25 | American: +225 | Fractional: 9/4 | Implied: 30.77% | Profit: $112.50
Formula
Implied Probability = (1 / Decimal Odds) x 100
All odds formats can be converted through decimal odds as an intermediary. Decimal odds represent total return per unit staked. Dividing 1 by decimal odds gives the implied probability, which is the foundation for all conversions.
Worked Examples
Example 1: Converting Decimal Odds to All Formats
Problem:A bookmaker offers decimal odds of 3.25 on a football match. Convert to all formats and calculate payout on a $50 bet.
Solution:Decimal: 3.25 American: (3.25 - 1) x 100 = +225 Fractional: 2.25/1 = 9/4 Implied Probability: (1/3.25) x 100 = 30.77% Hong Kong: 3.25 - 1 = 2.25 Payout: $50 x 3.25 = $162.50 Profit: $162.50 - $50 = $112.50
Result:Decimal: 3.25 | American: +225 | Fractional: 9/4 | Implied: 30.77% | Profit: $112.50
Example 2: Converting American Odds (Favorite)
Problem:A tennis player is listed at -180 American odds. Convert and calculate payout on a $200 bet.
Solution:American: -180 Decimal: (100/180) + 1 = 1.5556 Fractional: 0.5556/1 = 5/9 Implied Probability: (1/1.5556) x 100 = 64.29% Hong Kong: 0.5556 Payout: $200 x 1.5556 = $311.11 Profit: $311.11 - $200 = $111.11
Result:Decimal: 1.5556 | Fractional: 5/9 | Implied: 64.29% | Profit: $111.11
Frequently Asked Questions
What are the main odds formats used in sports betting worldwide?
The three primary odds formats are decimal (European), fractional (British), and American (moneyline). Decimal odds represent the total payout per unit staked, including your stake, so 2.50 means you receive $2.50 for every $1 wagered. Fractional odds show profit relative to stake, so 3/2 means $3 profit for every $2 staked. American odds use a baseline of $100: positive odds like +150 show profit on a $100 bet, while negative odds like -200 show how much you must bet to win $100. Beyond these, Hong Kong odds show profit per unit (similar to fractional but as a decimal), Indonesian odds work like American but based on 1 unit instead of 100, and Malay odds have their own inverted format popular in Southeast Asian markets.
How do you convert between decimal and American odds?
Converting between decimal and American odds follows two rules depending on whether the decimal odds are above or below 2.0 (even money). For decimal odds of 2.0 or higher (underdog), subtract 1 then multiply by 100 to get positive American odds. For example, decimal 3.50 becomes (3.50 - 1) x 100 = +250. For decimal odds below 2.0 (favorite), divide -100 by the decimal minus 1. For example, decimal 1.50 becomes -100 / (1.50 - 1) = -200. Going the other direction: positive American odds are divided by 100 then add 1 for decimal. So +250 becomes (250/100) + 1 = 3.50. Negative American odds use 100 divided by the absolute value then add 1. So -200 becomes (100/200) + 1 = 1.50.
What is implied probability and how does it relate to odds?
Implied probability converts odds into a percentage representing the likelihood of an outcome as suggested by the odds. It is calculated as 1 divided by the decimal odds, then multiplied by 100. Decimal odds of 2.00 imply a 50% probability. Odds of 4.00 imply 25%. Odds of 1.25 imply 80%. Understanding implied probability is crucial because it allows bettors to compare bookmaker odds against their own estimated probability of an outcome. If you believe a team has a 60% chance of winning but the odds imply only 45%, the bet offers positive expected value. However, bookmaker margins mean the sum of implied probabilities for all outcomes exceeds 100%, creating the overround or vigorish that represents the bookmaker profit margin.
What is the overround and how does it affect betting odds?
The overround, also called vigorish or juice, is the built-in profit margin that bookmakers embed in their odds. In a fair market, the implied probabilities of all possible outcomes sum to exactly 100%. Bookmakers set odds so this sum exceeds 100%, with the excess being their margin. For example, in a two-outcome event, a fair coin flip would be 2.00 on each side (50% + 50% = 100%). A bookmaker might offer 1.91 on each side, implying 52.4% each, totaling 104.7%. The 4.7% overround is the bookmaker margin. Lower overrounds indicate more competitive odds and better value for bettors. Sharp bettors always compare overrounds across bookmakers to find the best value and minimize the house edge on their wagers.
How do Hong Kong, Indonesian, and Malay odds formats work?
These three Asian odds formats each represent payouts differently and are widely used in their respective regional markets. Hong Kong odds show the net profit per unit staked, essentially the decimal odds minus 1. So Hong Kong odds of 1.50 equal decimal 2.50, meaning $1.50 profit per $1 bet. Indonesian odds work similarly to American odds but use 1 unit instead of 100 as the base. Positive Indonesian odds of 1.50 mean $1.50 profit per $1 bet (same as Hong Kong). Negative Indonesian odds of -1.50 mean you risk $1.50 to win $1. Malay odds are inverted from Indonesian: positive Malay odds below 1.0 represent underdogs showing your profit per unit, while negative Malay odds show what you risk to win one unit. These formats are standard across Asian sportsbooks and betting exchanges in the region.
What is the difference between odds and probability?
Probability is expressed as a number between 0 and 1 (or a percentage), representing the likelihood of an event. Odds compare favorable outcomes to unfavorable ones — odds of 3:1 means 3 wins for every 1 loss, which is a probability of 3/(3+1) = 75%. Casinos often express odds differently from true probability to build in their house edge.
References
Reviewed for accuracy by Daniel Agrici, Founder & Lead Developer · Editorial policy
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