It’s important to note that fixed odds aren’t “fixed” until a bet is placed. If you monitor a betting market, you’ll notice that the odds fluctuate. This is because they’re regularly updated to reflect changes in factors that affect bookmakers’ calculations of the probabilities of different outcomes.
Once you've placed a bet, however, you're shielded from any further changes to the relevant odds.
What do fixed odds represent?
The odds in pool bets indicate which selections are attracting the most bets and the amount of money in the pool. Fixed odds are, however, linked to probability calculations.
When they’re displayed as fractional odds, fixed odds for a selection come close to representing the true, relative probability of that selection being successful. Fixed odds don’t represent probability perfectly because bookmakers adjust the odds downwards in order to generate revenue from betting markets.
Fixed odds formats
Fixed odds are displayed in a variety of formats, including fractional odds, decimal odds and moneyline odds. British bookmakers tend to use fractional odds, European bookmakers prefer decimal odds and Americans and Australians tend to prefer moneyline odds.
Most online bookmakers let you use account settings to choose the format in which you want their fixed odds to display – so you can choose the format you’re most comfortable using.