Every set of betting odds contains a hidden probability. Understanding implied probability is the first step to analysing whether you are getting good value — or giving your money away.
Implied probability is the percentage chance of an outcome that is built into the bookmaker's odds. It is called "implied" because it is not stated directly — you derive it from the price.
For decimal odds, the conversion is straightforward:
The implied probability is the bookmaker's assessment of how likely an outcome is, after including their margin. A higher implied probability means a stronger favourite; a lower one means an underdog.
Most common in the UK and Europe. Divide 1 by the decimal price.
Common in UK horse racing. Divide the denominator by the total (numerator + denominator).
Used in the US. Positive odds (underdog) and negative odds (favourite) use different formulas.
If you add up the implied probabilities for all outcomes of a match — home win, draw, and away win — they should sum to 100%. In reality, they sum to more than 100%. The excess is the bookmaker's profit margin, called the overround or vig.
For example, if a match has the following odds:
Home win
2.10
47.6%
Draw
3.40
29.4%
Away win
3.80
26.3%
Total: 103.3% — overround of 3.3%
This means every pound bet into this market loses an average of 3.3p to the bookmaker before the bet even starts. The lower the overround, the better value you are getting.
The gap between the bookmaker's implied probability and your own probability estimate is where value lives. The process:
You do not need to be right every time. You just need your edge per bet to be greater than the overround to profit long-term.
Not all bookmakers are equal. Sharp bookmakers (like Pinnacle) operate at very low margins of 1–3% because they accept sharp bettors and let the market price set itself. Soft bookmakers have higher margins of 7–15% but offer better bonuses and are more willing to take losing bettors' money.
Sharp books' prices are widely used as a benchmark. If a sharp book prices a team at 2.10 and a soft book prices them at 2.40, the soft book's odds may represent value relative to the true market probability.
What is implied probability in betting?
Implied probability is the percentage chance of an outcome embedded in the bookmaker's odds. It is calculated by dividing 1 by the decimal odds. Odds of 3.00 imply a 33.3% probability.
What is the bookmaker overround?
The overround is the bookmaker's profit margin. If you add up the implied probabilities for all outcomes of a match, they sum to more than 100%. The excess percentage is the overround — the house edge built into every market.
How do I find fair odds from implied probability?
Remove the bookmaker margin by dividing each individual implied probability by the total sum of all implied probabilities in the market. This gives you the "true" or "fair" probability without the margin.
What is a value bet in terms of implied probability?
A value bet is one where your estimated true probability is higher than the bookmaker's implied probability. If you believe a team has a 55% chance of winning but the odds imply only 45%, the bet has positive expected value.
Convert any odds with KiqIQ's free calculators
The Implied Probability Calculator converts any odds format to probability instantly. The Margin Calculator shows you exactly how much the bookmaker is taking.
For informational and entertainment purposes only. Not betting advice. Disclaimer
