The Court

A tennis court is 78 ft (23.77 m) long — and this length never changes, for singles or doubles. What changes is the width.

Singles courts are 27 ft (8.23 m) wide; doubles courts open out to 36 ft (10.97 m). The net cuts the rectangle exactly in half: 39 ft (11.89 m) from the net to each baseline.

All lines belong to the court. A ball touching any part of a line is in — lines are measured to their outer edge.

Each white line has a name and a job. The baselines run along the back; the sidelines run the length on each side, in two pairs — singles (inner) and doubles (outer). The strip between them is the alley (also called the tramline), 4.5 ft (1.37 m) wide, live only in doubles.

Parallel to the net, 21 ft (6.40 m) away on each side, runs the service line. Down the middle between the two service lines runs the centre service line, splitting the forecourt into two service boxes. A small centre mark, 4 in (10 cm) long, sits at the middle of each baseline — your reference for serving.

The net stands 3 ft (0.914 m) high at the centre, held down there by a white centre strap (no wider than 2 in / 5 cm), and rises to 3 ft 6 in (1.07 m) at the posts. The net posts sit 3 ft (0.914 m) outside the doubles sideline on each side.

When singles is played on a doubles court, singles sticks prop the net up 3 ft outside each singles sideline — that's why the net seems to sag less in a "real" singles match. A clean white band runs along the top edge of the net.

Each side of the net has two service boxes, bounded by the net, the service line, and the centre service line. Each box is 21 ft (6.40 m) deep × 13.5 ft (4.11 m) wide — half of the 27 ft singles width. The alleys are never part of the service box; even in doubles, you serve into the singles-width box.

The right-hand box (from the server's view) is the deuce court; the left-hand box is the ad court. Serves are struck diagonally into the box opposite. Where the centre service line meets the service line is the "T" — a prime serving target and a key recovery spot for the server after their delivery.

Players carve the court into a few familiar zones. They aren't drawn on the surface, but every coach and commentator names them constantly.

Same length, different width. Singles uses only the inner court; doubles "switches on" the two alleys. The serving target is identical in both — always the singles-width box.

A court doesn't end at the baseline. Behind each baseline, allow at least 21 ft (6.40 m) of run-back so players can chase deep balls; beyond each sideline, at least 12 ft (3.66 m) of run-off.

A comfortable single court therefore needs roughly 120 ft × 60 ft (36.6 m × 18.3 m) in total. Anything less and the rectangle starts to feel smaller than the rules suggest.

Keep these by your racket bag. Metric and imperial, side by side.

A full court is a long way to ask a seven-year-old to run. For most of the game's history that was simply the deal — children swung on adult courts with adult balls and waited for their reach to catch up. The modern game no longer asks them to wait. Under the ITF's Tennis 10 and Under programme — better known as Play and Stay — the court itself is scaled to the player, shrunk to a beginner's size and then grown back to full over three colour-graded stages.

The smallest is the red court, the true starting point and the one coaches tend to call the kids' court. It runs about 11 metres by 5.5 metres — roughly 36 by 18 feet — small enough that two of them fit side by side across a single adult court. The net sits lower, near 0.8 metres, and the ball is a soft, slow red one that floats long enough for a child to reach it and swing. Rackets here stay under 23 inches. It is tennis at walking pace, and it is where almost every player now alive first met the sport.

Next comes the orange court, the middle stage — the mid court. It stretches to roughly 18 metres by 6.4 metres, about three-quarters of the real thing, and the net rises to its standard 0.914 metres at the centre. The orange ball travels faster than the red but still around half the speed of a championship ball, which is enough to reward the longer rallies and fuller swings a slightly older player can now produce.

Last before the full game is the green court, which is no longer cut down at all. It uses the complete adult court, the standard net and adult-length rackets; only the ball is held back — a green-dot ball about a quarter slower than yellow — to soften the jump in pace. Clear that, and the player walks onto the same 23.77-metre court described at the top of this chapter, yellow ball in play, with nothing left between them and the whole sport.