Editing Odds (section)

==Gambling usage==
{{see also|Fixed-odds betting|Parimutuel betting}}
On a [[coin toss]] or a [[match race]] between two evenly matched horses, it is reasonable for two people to wager level stakes. However, in more variable situations, such as a multi-runner horse race or a football match between two unequally matched teams, betting "at odds" provides the possibility to take the respective likelihoods of the possible outcomes into account. The use of odds in gambling facilitates betting on events where the probabilities of different outcomes vary. 

In the modern era, most fixed-odd betting takes place between a betting organisation, such as a [[bookmaker]], and an individual, rather than between individuals. Different traditions have grown up in how to express odds to customers.

===Fractional odds===
Favoured by [[bookmaker]]s in the [[United Kingdom]] and [[Ireland]], and also common in [[horse racing]], fractional odds quote the net total that will be paid out to the bettor, should they win, relative to the stake.<ref name="Goal"/> Odds of 4/1 (''4 to 1 against'') would imply that the bettor stands to make a £400 profit on a £100 stake. If the odds are 1/4 (''1 to 4 against'', ''4 to 1 in favor'', or ''4 to 1 on''), the bettor will make £25 on a £100 stake. In either case, having won, the bettor always receives the original stake back; so if the odds are 4/1 the bettor receives a total of £500 (£400 plus the original £100). Odds of 1/1 are known as ''evens'' or ''even money''.

The [[numerator]] and [[denominator]] of fractional odds are often [[integer]]s, thus if the bookmaker's payout was to be £1.25 for every £1 stake, this would be equivalent to £5 for every £4 staked, and the odds would therefore be expressed as 5/4. However, not all fractional odds are traditionally read using the [[lowest common denominator]]. For example, given that there is a pattern of odds of 5/4, 7/4, 9/4 and so on, odds which are mathematically 3/2 are more easily compared if expressed in the equivalent form 6/4.

Fractional odds are also known as ''British odds,'' ''UK odds,''<ref name="wbx"/> or, in that country, ''traditional odds''. They are typically represented with a "/" but can also be represented with a "-", e.g. 4/1 or 4–1. Odds with a denominator of 1 are often presented in listings as the numerator only.{{citation needed|date=May 2016}}

A variation of fractional odds is known as ''Hong Kong'' odds. Fractional and Hong Kong odds are actually exchangeable. The only difference is that the UK odds are presented as a fractional notation (e.g. 6/5) whilst the Hong Kong odds are decimal (e.g. 1.2). Both exhibit the net return.

===Decimal odds===

The European odds also represent the potential winnings (net returns), but in addition they factor in the stake (e.g. 6/5 or 1.2 plus 1 = 2.2).<ref name="SW1"/>

Favoured in continental [[Europe]], [[Australia]], [[New Zealand]], [[Canada]], and [[Singapore]], decimal odds quote the ratio of the payout amount, ''including'' the original stake, to the stake itself. Therefore, the decimal odds of an outcome are equivalent to the decimal value of the fractional odds plus one.<ref name="Betstarter"/> Thus even odds 1/1 are quoted in decimal odds as 2.00. The 4/1 fractional odds discussed above are quoted as 5.00, while the 1/4 odds are quoted as 1.25. This is considered to be ideal for [[Parlay (gambling)|parlay]] betting, because the odds to be paid out are simply the product of the odds for each outcome wagered on. When looking at decimal odds in betting terms, the underdog has the higher of the two decimals, while the favorite has the lower of the two. To calculate decimal odds, you can use the equation ''Payout = Initial Wager × Decimal Value''<ref>{{Cite web |date=25 January 2022 |title=Understanding Sports betting odds and how to read them |url=https://theathletic.com/2497657/2022/01/25/understanding-sports-betting-odds-and-how-to-read-them/ |access-date=25 September 2022 |website=The Athletic}}</ref>''.'' For example, if you bet €100 on Liverpool to beat Manchester City at 2.00 odds the payout, including your stake, would be €200 (€100 × 2.00). Decimal odds are favoured by [[betting exchanges]] because they are the easiest to work with for trading, as they reflect the reciprocal of the probability of an outcome.<ref name="Cortis"/> For example, a quoted odds of 5.00 equals to a probability of 1 / 5.00, that is 0.20 or 20%.

Decimal odds are also known as ''European odds'', ''digital odds'' or ''continental odds.''<ref name="wbx"/>

===Moneyline odds===
{{main|Moneyline odds}}
Moneyline odds are favoured by American bookmakers. The figure quoted is either positive or negative.
* When moneyline odds are positive, the figure indicates the net winnings for a $100 wager (this is done for an outcome that is considered less probable to happen than not). For example, net winnings of 4/1 would be quoted as +400.
* When moneyline odds are negative, the figure indicates how much money must be wagered to for a net winning of $100 (this is done for an outcome that is considered more probable to happen than not). For example, net winnings of 1/4 would be quoted as −400.

Moneyline odds are often referred to as ''American odds''. A "moneyline" wager refers to odds on the straight-up outcome of a game with no consideration to a [[Spread betting|point spread]]. In most cases, the favorite will have negative moneyline odds (less payoff for a safer bet) and the underdog will have positive moneyline odds (more payoff for a risky bet). However, if the teams are evenly matched, ''both'' teams can have a negative line at the same time (e.g. −110 −110 or −105 −115), due to house take.

===Wholesale odds===
Wholesale odds are the "real odds" or 100% probability of an event occurring. This 100% book is displayed without any [[bookmaker]]'s [[profit margin]], often referred to as a bookmaker's "[[overround]]" built in.

A "wholesale odds" [[Index (economics)|index]] is an index of all the prices in a probabilistic market operating at 100% competitiveness and displayed without any profit margin factored for market participants.