Tennis court guide

How big is a tennis court?

A tennis court is 78 feet (23.77 m) long and 36 feet (10.97 m) wide. That full width is for doubles; for singles the court narrows to 27 feet (8.23 m) and you simply ignore the outer lane on each side. The net stands 3 feet high at the center. Every regulation court on earth uses these exact numbers — and they've barely moved since 1877.

Length: 78 ft (23.77 m)
Width — doubles: 36 ft (10.97 m)
Width — singles: 27 ft (8.23 m)
Doubles alley: 4.5 ft (1.37 m) each side
Net height — center: 3 ft (0.91 m)
Net height — posts: 3 ft 6 in (1.07 m)
Service box: 21 ft × 13.5 ft
Playing area — doubles: 2,808 sq ft (260.9 m²)

Why this exact size?

The dimensions look arbitrary until you learn they're a compromise that got frozen in place. Tennis grew out of an 1870s lawn game, and the first standardized court wasn't even rectangular — Major Walter Wingfield's 1874 patent described an hourglass court, pinched in at the net and wider at the baselines, marketed in a box as "Sphairistikè."

That shape didn't last. When the All England Croquet Club set out to run the first Wimbledon in 1877, a three-man subcommittee threw out the hourglass and drew a plain rectangle 78 feet long and 27 feet wide. They borrowed the 78-foot length and the net concept from real tennis (the older indoor game), and picked a width that suited the singles match they were standardizing. Those 1877 numbers — 78 by 27, net at the posts — are essentially the court you still play on.

The length has a quiet logic to it: 78 feet is long enough that a hard serve can be returned but short enough to keep rallies alive, and 39 feet from net to baseline turned out to reward both power and patience. Nobody re-optimized it. It worked, the sport exploded, thousands of courts got built to match, and changing it later became unthinkable. The court is the size it is largely because that's the size it was.

Why some courts have lines on the sides and others don't

Here's the part that confuses newcomers: look at a court and you'll see two long lines running down each side, a few feet apart. That gap is the doubles alley (also called the tramline), and it's why a court can be two different widths without repainting anything.

The inner sideline marks the 27-foot singles court. In a singles match, a ball landing in the alley is out.
The outer sideline marks the full 36-foot doubles court. In doubles, that same alley is in — the extra 4.5 feet on each side is live.
The alley only applies down the sides. The service boxes and baselines are identical for both games; doubles just widens the court after the serve.

So when you see a court with only one line down each side — common on older public courts, school courts, or backyard builds — it was painted for singles only. A full doubles court adds the second, outer line to open up the alleys. Same length, same net, same service boxes; the side lines are the entire difference between the two games' footprints.

What actually varies between courts

The painted playing area never changes. What differs from court to court is everything around and beneath it:

Run-off space — the ITF recommends 21 ft behind each baseline and 12 ft beside each sideline, so a proper court needs about 120 ft × 60 ft of ground. Cramped public courts skimp here; tournament courts don't.
Surface — hard, clay, or grass changes how the ball bounces and how long points last, but not the dimensions.
Net detail — 3 ft at the center, 3 ft 6 in at the posts. The sag is intentional and identical everywhere.
Ceiling height (indoor) — the ITF wants ~30 ft of clearance over the net so lobs stay in play.

A tight neighborhood court and Centre Court at Wimbledon share the exact same lines. The difference you feel is the breathing room around them.

Quick comparisons

A pickleball court (44 ft × 20 ft) fits inside one tennis court nearly four times over — which is why one tennis court can host up to four pickleball games.
A basketball court (94 ft × 50 ft) is both longer and wider than a tennis court's playing lines.
A doubles tennis court is roughly 1/15th the size of an American football field.

Now that you can read the lines, go use them. Find a court near you and a partner to meet there.