Calculate the bookmaker overround from decimal odds in 2-way and 3-way markets — implied probabilities, total margin %, and fair no-vig odds.
Overround Calculator
Calculate the bookmaker overround from decimal odds — implied probabilities, total margin %, and fair no-vig odds.
Outcome 1 Implied Probability
47.6%
Fair odds: 2.20
Outcome 2 Implied Probability
29.4%
Fair odds: 3.57
Outcome 3 Implied Probability
27.8%
Fair odds: 3.77
Total Overround
4.81%
Bookmaker margin
✨ Key Capabilities
Implied probability for every outcome from decimal odds
Total overround % — the bookmaker's built-in margin
Fair no-vig odds for each outcome
Supports 2-way and 3-way markets
Instant recalculation as you type
📖 How to Use the Overround Calculator
Choose a 2-way or 3-way market.
Enter the decimal odds for each outcome.
View the implied probabilities, the total overround %, and the fair no-vig odds.
❓ Frequently Asked Questions
What is the overround?
The overround is the total of all implied probabilities in a betting market minus 100%. If the implied probabilities add up to 105%, the bookmaker's overround is 5% — that is their built-in margin.
What are fair no-vig odds?
Fair no-vig odds are the odds you would get if the bookmaker took no margin. They are calculated by removing the overround from each outcome's implied probability, and they show the bookmaker's true estimate of each outcome.