Course 6 • 4 Modules • 20 Lessons
Converting implied probability into fractional, decimal, and American odds
Understanding the relationship between probability and odds is fundamental to sportsbook operations. Every betting market is built on the concept of implied probability—the likelihood of an outcome occurring as expressed through the odds. A skilled trader must be able to convert seamlessly between different odds formats and understand what each implies about the underlying probability.
Decimal odds (common in Europe and Australia) represent the total return on a £1 stake. Odds of 2.00 mean you receive £2 back (including your stake), implying a 50% probability. Fractional odds (traditional in UK horse racing) show profit relative to stake—5/1 means £5 profit on a £1 bet, implying approximately 16.67% probability. American odds use positive and negative numbers relative to $100.
The conversion formulas are essential tools: Implied Probability = 1/Decimal Odds × 100. For fractional odds, it's Denominator/(Numerator + Denominator) × 100. Mastering these conversions allows traders to quickly assess value and compare markets across different platforms and regions.