What does double fault mean?
In tennis, each point begins with a serve. The server has two attempts to land the ball legally in the diagonally opposite service box. A fault occurs when the first attempt fails, either by hitting the net, landing outside the service box, or missing the box entirely. The server then gets a second attempt.
A double fault occurs when both serve attempts fail. The server loses the point immediately, and it is awarded to the opponent without any rally taking place. It is the only way a server can lose a point immediately without a rally beginning.
One important distinction: a let occurs when the serve clips the net and still lands in the correct service box. A let is not a fault. The serve is replayed, and neither attempt counts.
Double fault bet types
Total double faults (over/under, combined)
The most common double fault market. The sportsbook sets a combined line for both players across the full match, and you choose whether the total will finish over or under that number.
Example:
- Total double faults line set at 5.5
- Over at -110 (1.91)
- Under at -120 (1.83)
- Player A commits 3 double faults
- Player B commits 4
- Total: 7. Over wins
Total double faults (over/under, individual player)
The same over/under format applied to one player's double fault count only. Lines are set based on that player's serving tendencies and the match format.
Example:
- Player A over 2.5 double faults at +115 (2.15)
- Player A commits 4 double faults across the match
- Over wins.
Most double faults
A two-way market on which player will commit more double faults across the full match. Both players are listed with their respective odds. Some sportsbooks include a tie option.
Example:
- Player A most double faults +105 (2.05)
- Player B most double faults -130 (1.77)
- Player A commits 5
- Player B commits 3
- Player A wins the market
Double fault bet vs. related markets
Double fault vs ace bet
Aces and double faults are opposite outcomes of the serve. An ace wins the point outright for the server. A double fault gives the point directly to the opponent. Both follow the same over/under and most structure as betting markets. A player can record a high ace count and a high double fault count in the same match, particularly among aggressive servers who go for pace on both first and second serves.
Double fault vs aces and double faults combined
Some sportsbooks offer a single combined market covering the total of both aces and double faults across the match. This is a separate market from each individual stat. The combined line is set higher than either standalone market because it adds two different serve outcomes together.
How match format affects double fault totals
The number of sets played affects how many serves occur in a match, and therefore how many double faults are possible. Men's Grand Slam matches are best-of-five sets, while women's matches at Grand Slams and most other tournaments are best-of-three. Because best-of-five matches involve more service points, sportsbooks typically set higher double fault lines. For example, a combined line of around 5.5 in a best-of-three match may rise to 8.5 or higher in a best-of-five, depending on the players and sportsbook.
Based on ATP Tour data analysed by Tennis Abstract, the average double fault rate is approximately 3.9% of service points on the ATP and 5.1% on the WTA. Some limited analysis, including 2023 ATP data from the Sports Analytics Group at Berkeley, suggests grass courts may produce slightly higher double fault rates than clay or hard courts, although this finding is based on a small sample and may be influenced by outliers.
Settlement rules
Double fault markets are settled based on official tournament statistics, per standard sportsbook rules. If a match starts but is not completed, double fault bets are typically voided and stakes returned, unless the outcome of the specific market has already been determined before the match stopped.
Double faults committed during tiebreaks count toward the total in most sportsbooks, as tiebreak points follow the same serving rules as regular games. Always confirm whether the market covers the full match or a specific set before placing, as some sportsbooks offer set-specific double fault markets alongside the full-match version.
Where double fault markets are available
Double fault betting is most widely available for elite tournaments where statistical tracking is comprehensive.
- ATP and WTA Grand Slams (Australian Open, French Open, Wimbledon, US Open)
- ATP Masters 1000 and WTA 1000 events
- ATP Finals and WTA Finals
Market availability narrows considerably for ATP Challenger and ITF events. At that level, most sportsbooks offer only match winners and total games.
Conclusion
A double fault occurs when a server misses both serve attempts on the same point, immediately handing the point to the opponent. Betting markets around it follow the same over/under and most structure as other prop markets, settling on official tournament statistics after the match concludes.
For more explanations of betting markets and terminology, visit The Advantage blog.
Frequently asked questions
Does a let count as a double fault?
No. A let occurs when the serve clips the net and still lands in the correct service box. The serve is replayed and does not count as a fault toward a double fault.
What is the difference between a fault and a double fault?
A fault is a single failed serve. The server gets a second attempt. A double fault is when both attempts fail on the same point. The server loses the point immediately.
Does a double fault count if the receiver is not ready?
No. If the receiver was not ready and did not attempt to return the first serve, that serve is replayed. The double fault rule only applies to valid serve attempts.
Do double faults count in tiebreaks?
Yes. Double faults in tiebreaks count toward total and player prop markets, as they follow the same serving rules as regular games.
Can you bet on double fault markets in-play?
Yes. Total double fault lines update in-play as the match progresses. For a broader look at how live markets work, see our guide to live betting.