Proofset AcademyModule 1 · Professional tennisLesson 1.4Free · 25 min

Surfaces

Hard, clay, grass, indoor: the surface changes the speed of the ball, the height of the bounce and the way players move. So it changes who wins the points, and sometimes who wins the match.

Part 1

The four surfaces

Choose a surface: the photo, the indicators and the fact sheet change.

  • Speed
  • Bounce height
  • Weight of the serve
What is it made of?
What it feels like on court
Who it suits

Indicators out of 5: general orders of magnitude, not a Proofset measurement. The measurements are in part 3.

Part 2

How the speed of a court is measured

The International Tennis Federation (ITF) classifies surfaces into five speed categories, based on a rating measured in a laboratory, the Court Pace Rating. The higher the rating, the more the ball keeps its speed after the bounce.

1Slow
2Medium-slow
3Medium
4Medium-fast
5Fast
Clay
Hard
Indoor
Grass

The ranges are typical positions: each tournament chooses its surface, and two hard courts can be very different. The 5-category scale is the ITF’s.

Part 3 · Proofset measurement

What our data show

Over the last 12 months, the Proofset database contains about 33 000 matches with full statistics: 20 187 on hard courts (indoor included), 11 401 on clay and 1 442 on grass. Here is what the surface changes, on average, for the server.

Proofset database, matches from 14/10/2025 to 13/10/2026, all tours in the database, men and women combined. Hard and indoor courts are not separated in our data. Grass-court matches are also longer because men’s matches at Wimbledon are played to 3 winning sets.

Key takeaway: on grass, the server holds serve almost 8 times out of 10 and hits more aces. On clay, the server hits half as many and loses serve more often: breaks are more frequent, and a match swings more easily.

Part 4 · Proofset measurement

The surface calendar

The season changes surface several times. Each column shows the share of matches played on each surface that month, in the Proofset database.

Hard and indoorClayGrass

How to read it: from January to March, almost everything is played on hard courts (90 % of matches in January). From April to July, clay dominates. Grass only really appears in June, and even then it accounts for only 20 % of matches. In autumn, play returns to hard courts, often indoors.

Proofset database, October 2025 to October 2026, all tours. The lower-tier tours play a lot on clay in summer, which probably explains the share of clay in July.

Part 5

The bounce, side by side

The same shot, on four surfaces. On clay, the ball slows down and bounces high. On grass, it skids through and stays low: the opponent has less time to return serve.

shot net bounce

Illustrative diagram, not to scale.

Part 6

What the surface changes for players

On clay

Players slide to reach the ball. Rallies are long, requiring stamina and patience. Players who hit with a lot of topspin benefit from the high bounce.

On grass

Points are short and the serve often decides the game. Footing is tricky and the ball stays low: players have to bend their knees and play fast.

On hard courts

The all-round surface: a consistent bounce, medium speed. It is the surface on which the most tournaments are played, so the one where players have the most reference points.

Indoors

No wind, no sun, no heat: conditions are stable from one day to the next. Good servers are often comfortable there.

The specialist: some players win far more on one surface than on the others. Their ranking, which mixes all surfaces, then underestimates them on their preferred surface and overestimates them elsewhere.

Transitions: moving from clay to grass in June means changing footwork and timing within a few days. The first tournaments after a change of surface are often the most unpredictable.

Why it matters for a bet

  • Level depends on the surface. That is why the Proofset ELO has a component for each surface, in addition to the overall component: a player does not have the same rating on clay and on grass.
  • Grass offers few reference points. It accounts for only 1 442 matches over 12 months in our database, against more than 20 000 on hard courts. Grass ratings are therefore based on fewer matches.
  • On clay, the serve protects less: 68,9 % of service games won, against 77,8 % on grass. A one-break deficit is recovered more often there.
  • After a change of surface, a player’s latest results were obtained on another surface. Recent form should then be read with caution.
Part 7

Test yourself

5 questions. You need 4 correct answers to pass the lesson.

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