Tennis court geometry
Every measurement on a tennis court and the rule that governs them all — court and service-box dimensions, line widths, the centre mark, and why measurements are taken to the outside of the lines.
Overview
The court is a rectangle 78 feet (23.77 m) long. For singles it is 27 feet (8.23 m) wide; for doubles, 36 feet (10.97 m). The same rectangle serves both, with the doubles tramlines simply out of play in singles.
The service lines are drawn 21 feet (6.40 m) from each side of the net, parallel with it. The area between each service line and the net is divided into two equal service courts by the centre service line, drawn parallel with the singles sidelines and half-way between them.
The rule that governs every other measurement
All court measurements shall be made to the OUTSIDE of the lines. This one sentence decides what every other figure means: the 78 feet is measured to the outer edge of the baselines, and the 27 feet to the outer edge of the singles sidelines.
It follows that the lines are inside the court they bound. A ball touching any part of a line is good — the line belongs to the court, and the playing area is measured to its far edge.
Line widths are specified, and one is different
All lines of the court shall be between 1 inch (2.5 cm) and 2 inches (5 cm) wide, except that the baselines may be up to 4 inches (10 cm) wide. All lines must be of the same colour, clearly contrasting with the surface.
The baseline exception exists because the baseline is the most-watched line on the court and the one most often called on. A wider line is easier to judge against from the umpire's chair and from the line positions.
The centre mark
Each baseline is divided in half by a centre mark 4 inches (10 cm) in length, drawn INSIDE the court and parallel with the singles sidelines.
It is drawn inside deliberately, because it defines where the server may stand: the server must be within the imaginary extensions of the centre mark and the sideline, and must not touch the imaginary extension of the centre mark with either foot. A mark drawn outside would put that boundary in the wrong place.
Advertising
No advertising is allowed on the court, net, strap, band, net posts or singles sticks except as provided in Appendix V of the Rules.
This is unusually restrictive by modern sporting standards and is worth knowing when reading a court diagram: markings that appear on a televised court are not necessarily permitted under the Rules themselves.
Good to know
- The court is 78 ft (23.77 m) long, 27 ft (8.23 m) wide for singles and 36 ft (10.97 m) for doubles.
- Service lines sit 21 ft (6.40 m) from each side of the net.
- All measurements are made to the outside of the lines, so lines are inside the court.
- Lines are 1–2 in (2.5–5 cm) wide, except baselines which may be up to 4 in (10 cm).
- The centre mark is 4 in (10 cm) long and drawn inside the court.
Where it’s used
Sports that use tennis court geometry:
Sources
The rules, dimensions and specifications on this page were read from these documents.
- ITF Rules of Tennis — International Tennis Federation, 2026, Rule 1 — The court (read 2026-09-12)
How it connects
The meaning-bearing relationships that place Tennis court geometry in the wider knowledge graph — each one with the reason it exists.
Foundation of
These build directly on this one.
Explains
Covers the underlying "why" for these.
Explore across the knowledge base
Follow the threads that connect Tennis court geometry to the rest of SocialSportHub.
Equipment
- The tennis net, posts and singles sticksThe net's two heights and the hardware that holds them — post height and position, the singles sticks that convert a doubles net, and the strap and band that finish it.
- Wickets, stumps and bailsThe three stumps and two bails a bowler aims at and a batter defends — their exact height, width and shape, and what the Laws say about when bails may be dispensed with.
- The table tennis net assemblyThe net, its posts and its suspension — the one height that governs both the net and the posts, and why that number appears twice in the Laws.
- The goal and the creaseThe net a hockey team defends and the protected area in front of it — the exact goal dimensions, what the crease area includes, and why goaltender contact so often disallows a goal.
- Tennis ball types and specificationsThe four ITF ball types and what separates them — mass, size, rebound and deformation — plus the counterintuitive rule that fast balls are for slow courts.
Tactics
- Crosscourt and down the lineThe geometry that makes crosscourt the default tennis shot — the net is lower in the middle and the court is longer on the diagonal — and when down the line is worth its extra risk.
- Tennis doubles formationsHow doubles teams position and why — the standard one-up-one-back start, poaching, the Australian formation and the I-formation, and what each one takes away from the returner.
Rules
- Tennis serving rulesThe rules governing how a tennis point begins, including where the server stands and where the serve must land.
- Throw-inThe method of restarting football when the ball fully crosses a side line, taken by throwing it back into play.
- Cricket creasesThe white lines marked at each end of a cricket pitch — bowling, popping and return creases — what each one is for, and the exact measurements that decide no-balls, run-outs and stumpings.
- LetA call that stops a point and has it replayed without penalty, used across several racket sports.
- Leg before wicket (LBW)Cricket's most argued-about dismissal, set out as the Laws set it out: five conditions that must all be satisfied, and the one clause that changes everything if the batter played a shot.
Learning paths
Techniques
- Tennis ServeThe overhead stroke that starts every point, hit from behind the baseline into the diagonally opposite service box.
- Movement and recovery in tennisWhy tennis footwork is mostly about getting back rather than getting there — the split step, the recovery position that is not the centre of the court, and sliding on clay.
- Kicking in rugby unionThe kicks rugby union is played with — punt, grubber, box kick, up-and-under, drop kick and place kick — what each achieves and which law governs its use.
- Free ThrowAn unguarded basketball shot taken from the free-throw line, relying on a calm, repeatable routine rather than power.
How this page is maintained
- Content type
- Facility
- Provenance
- Tier A — evergreen educational
- Verified external sources
- 0
- Content updated
- 2026-09-01
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