Tennis betting odds represent the bookmaker's assessment of each player's chance together with a margin, and since a tennis match has just two possible outcomes, you can work out that margin for yourself in a matter of seconds. The page explains how the margin varies according to the level of tournament, how to convert odds into probabilities, and the reason why favourites have shorter odds in five-set matches. It uses simple arithmetic, so all you need is a calculator on your phone. All the figures in the examples are for illustrative purposes and have not been taken from any bookmaker.
Tennis Margin by Tournament Level
Tennis betting odds always include a margin, but this margin varies from place to place. It is typically smallest where the amount of betting and public data are greatest, so the type of tournament gives you a good indication of the kind of odds you can expect. The table illustrates this typical situation, not the exact figures.
| Tournament level | Typical margin | Reason |
|---|---|---|
| Grand Slams | Lowest | Huge betting volume and the most public information |
| ATP and WTA tour events | Low to medium | Large markets, but fewer bettors than at Grand Slams |
| Challenger | Medium to higher | Smaller markets and less data to price from |
| ITF | Highest | Very small markets and little reliable information |
| Live betting at any level | Higher than pre-match | Prices must change fast, so bookmakers add more protection |
Although some review websites state that the margin on 1xBet's main ATP and WTA match-winner markets is about 5%, this figure is not official, so you should check it for yourself using the method described in the following sections.
From Odds to Probability
The implied probability of a bet is obtained by dividing 1 by the decimal odds; the result is a number lying between 0 and 1, and when this number is multiplied by 100 it gives a percentage.
The following two examples illustrate how the system works. If the odds are 1.25 then 1 ÷ 1.25 = 0.80, which means the bookmaker is giving that player a probability of 80 per cent. When the odds are 4.00 then 1 ÷ 4.00 = 0.25, that being a 25 per cent chance. The higher the price the greater the implied probability and the longer the price the lower the probability.
A tennis match can only have two possible results, and therefore the two probabilities should total 100%. On an actual market, however, they do add up to more than 100%. For example, if one player is given odds of 80% and the other 25%, the total is 105%. The extra 5 percentage points is the margin, which is the bookmaker's built-in fee for providing the bet.
One thing should be kept in mind: implied probability represents the bookmaker's opinion, not the truth; it indicates what the price implies, and the actual probability could be either higher or lower.
How to Calculate the Margin on a Tennis Match
The margin in a two-way tennis market is calculated using the following formula: margin = (1 ÷ odds A + 1 ÷ odds B) − 1. To apply the formula, carry out the calculation in three steps: first, convert each price into the probability it implies; second, add those two probabilities together; third, subtract 1. The amount that remains is the margin, and when this margin is multiplied by 100 it gives the margin as a percentage.
| Match type | Odds A | Odds B | Implied A | Implied B | Sum | Margin |
|---|---|---|---|---|---|---|
| Even match | 1.85 | 1.95 | 0.5405 | 0.5128 | 1.0533 | about 5.3% |
| Favourite vs underdog | 1.40 | 2.90 | 0.7143 | 0.3448 | 1.0591 | about 5.9% |
You can use a phone's calculator to carry out this calculation for any match you intend to bet on. It is advisable to compare the margin for the same match a few minutes before the match starts, since a rising margin near the time of the match start is common. The two examples given are illustrative and not direct quotations from any bookmaker.
Best of Three vs Best of Five: Why Favourites Get Shorter
The majority of tennis matches go to three sets, but men's Grand Slam matches go to five, and a simple model explains why this affects the prices.
Say Player A wins any single set with probability p. The chance of winning a best-of-three match is p² × (1 + 2 × (1 − p)), and the chance of winning a best-of-five match is p³ × (1 + 3 × (1 − p) + 6 × (1 − p)²).
| Set win probability | Best-of-three match win | Best-of-five match win |
|---|---|---|
| 60% | about 64.8% | about 68.3% |
| 70% | about 78.4% | about 83.7% |
A player who wins 60% of the sets will win approximately 64.8% of best-of-three matches but around 68.3% of best-of-five matches. When the percentage per set rises to 70%, the corresponding win rate increases from 78.4% to 83.7%. Since longer matches allow the better player more time to recover, men's Grand Slam favourites are given shorter odds than they would be at a best-of-three event.
The model assumes that each set is independent, whereas real matches are not.
What Moves Tennis Odds Before the First Serve
The tennis odds offered by 1xBet may change in the hours leading up to a match, and the reason for most of these changes is obvious.
- News regarding fitness and possible withdrawals. Since news of a player having an injury or possibly withdrawing can cause prices to change rapidly, it is important to check the most recent news before placing a bet.
- Putting a lot of money on a single player; if many bettors choose the same side, the bookmaker might lower the odds for that side and increase the odds for the other in order to balance the risk.
- A switch of courts or changes in the circumstances — such as a roof being closed, moving to a different court, or a delay caused by rain — can advantage one type of player, hence the prices might be altered.
- The duration of the preceding round; a player who has just taken part in a long match, for example a five-setter, may be regarded as more tired and the price can take this into account.
- The schedule or the draw were only made known late. If the order of the matches is altered or if there is a late change of opponent, the price can be changed before the match starts.
A sharp fall in price counts as information, not as a guarantee, and therefore you should see it as a reason to look into it more rather than as a reason to make a bet. The same principles of margin and implied probability apply to cricket betting odds, which we also break down in a separate guide.
Betting should be a form of entertainment that you fund with money you are able and willing to lose. Before you begin, decide on a limit for how much you will deposit and one for how long you will bet, and always avoid trying to recover your losses. You should only place a bet when you are calm and not under the influence, and never bet money that you have borrowed. If betting ceases to be enjoyable, then take a break. The betting sites provide tools such as deposit limits, time-outs and self-bans, which you can access in your account settings. If betting is causing you problems, you should speak to someone you trust or contact a professional support service. 18+ only.
