A tennis court can look like a confusing grid of white lines the first time you really study it. But each line has a clear job, and once you know what they all mean the court becomes easy to read. Here is every marking explained, plus the dimensions that define a regulation court.
A tennis court is 78 feet long from baseline to baseline. The width depends on whether you are playing singles or doubles: 27 feet wide for singles and 36 feet wide for doubles. The extra 4.5 feet on each side — the doubles alleys — are in play only during doubles. The total playing surface, including room to move behind and beside the lines, is usually about 120 feet by 60 feet.
Each side of the net has two service boxes, each 21 feet deep and 13.5 feet wide. A serve must land in the box diagonally opposite the server. Importantly, the doubles alleys are not part of the service boxes — a serve into the alley is a fault even in doubles. The boxes are where every point begins, which is why holding serve depends so much on placement within them.
The net is 3 feet 6 inches (42 inches) high at the posts and sags to exactly 3 feet (36 inches) in the center, held down by a center strap. That dip is deliberate: it rewards players who hit through the middle of the court with a little more margin.
💡 Reading a new court quickly: find the two inner sidelines first. Everything inside them is the singles court; the corridors outside are only live in doubles. That one distinction clears up most of the confusion.
Many public facilities now paint pickleball lines onto existing tennis courts, so a single tennis court can host up to four pickleball courts. The result is a busier set of lines in a second color, which can be momentarily confusing but is easy to filter out once you know which sport you are playing. If you see two colors of lines, the smaller rectangles (44 by 20 feet) are pickleball. Our map flags courts that offer both sports — here is how the two games compare.
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