A court can look nearly right and still produce awkward calls if the service lines sit a few inches off or the sidelines are not square. The reliable way to mark one is to set out the full rectangle first, check it carefully, then add the service boxes and paint lines to a consistent width.
Know the court dimensions
A regulation tennis court is 78 feet long. Its width depends on the game: 36 feet for doubles and 27 feet for singles. The singles court sits inside the doubles court, leaving a 4.5-foot doubles alley on each side.
The net divides the court in half, 39 feet from either baseline. On each side, the service line is 21 feet from the net, so it is 18 feet from the baseline. The center service line divides the space between the singles sidelines into two service boxes, each 13.5 feet wide.
These are playing dimensions: measure to the outside edge of the boundary lines. Lines are part of the court, so measuring between their inner edges will make the playing area too small.
What you’ll need
- A long tape measure, preferably 100 feet or longer
- Measuring tape or a marked cord for shorter distances
- Chalk, removable marking paint, or stakes and string for layout
- Masking tape or a line-marking machine, depending on the surface
- Paint made for tennis courts, if marking a permanent hard court
- A helper to hold the tape, string, or chalk line
Check the court surface before choosing a marking method. Acrylic hard courts need compatible sports-court paint; ordinary household paint can wear poorly or create a slippery surface. On clay, use the court’s usual line-marking material and a line-marking machine. Grass courts typically use a suitable temporary marking product. Follow the surface manufacturer’s instructions, and do not paint over a court without permission if it is shared or maintained by someone else.
How to mark the court
1. Choose and prepare the site
Clear away debris and check that the ground is level enough for play. A regulation court needs more room than the painted rectangle: players need space to run beyond the baselines and sidelines. If you are building a permanent court, plan the runoff area and drainage before marking lines. For a temporary court, make sure there is enough safe space around the playing area.
Decide whether you are laying out a doubles court, a singles-only court, or both. A full doubles court can also be used for singles by adding the two inner sidelines. If you want both formats, mark the 36-foot-wide rectangle first, then position singles sidelines 4.5 feet inside each doubles sideline.
2. Establish the outer rectangle
Mark one baseline and measure its full 36-foot width. Mark its midpoint, then use that point to set the net line at a right angle, 39 feet away. From the net line, measure another 39 feet to locate the far baseline. The outside rectangle should measure 78 by 36 feet.
Do not rely on sight alone to judge a right angle. A square layout has equal diagonals: for a 78-by-36-foot doubles court, each corner-to-corner diagonal is about 85 feet 11 inches. Measure both diagonals between corresponding outer corners; if they differ, adjust the corners and check again. A singles-only rectangle measuring 78 by 27 feet has diagonals of about 82 feet 7 inches.
For a smaller temporary layout, you can use a 3-4-5 triangle to create a right angle: measure three units along one side, four along the other, and adjust until the gap between those marks is five units. Use larger multiples, such as 6-8-10 feet, for a more dependable result.
3. Add the net and singles sidelines
Mark the center of each end of the net line. The net runs across the full doubles width, with its center aligned to the court’s center. The singles sidelines run parallel to the doubles sidelines, 4.5 feet inside them on each side. Check that each singles sideline is 78 feet long and that the distance between the two is 27 feet.
4. Measure the service lines and center lines
From the net line, measure 21 feet toward each baseline and mark the service line across the singles court width. Repeat on the other half. These lines should be parallel to the net and to the baselines. The center service line runs from the net to the service line on each side, splitting the 27-foot singles width into two 13.5-foot service boxes.
At the midpoint of each baseline, add a center mark that extends 4 inches into the court. It helps the server line up behind the correct half of the baseline. Keep the mark centered on the baseline.
5. Tape or mark the lines consistently
For most court lines, use a 2-inch width. The baseline may be wider—up to 4 inches—if the court’s design or the applicable rules allow it. Keep each line a consistent width, and make sure corners meet cleanly. The doubles alleys are the space between the singles and doubles sidelines; do not add a line down the middle of an alley.
On a hard court, snap chalk lines or use a line-marking machine to guide the layout, then mask the edges before applying court paint. Make sure the surface is clean and dry, apply the paint as directed, and remove masking tape at the recommended time. Let the markings cure fully before play. On clay, use the court’s standard method to set and secure the lines, then brush and roll the surface as usual.
Checks to make before playing
- Outer court: 78 feet long and 36 feet wide for doubles.
- Singles court: 78 feet long and 27 feet wide, centered inside the doubles court.
- Service lines: 21 feet from the net on both sides.
- Service boxes: 13.5 feet wide and 21 feet deep.
- Both corner-to-corner diagonals match.
- Lines are straight, easy to see, and the same width where required.
One useful final test is to stand behind each baseline and look down the sidelines. They should appear parallel, and the service lines should look parallel to the net. That visual check will not replace measuring, but it can reveal an obvious mistake before the paint dries.
Frequently Asked Questions
Can I mark a tennis court with chalk?
Chalk can work for a temporary layout on a suitable surface, but it may wash or brush away quickly. For a permanent hard court, use compatible sports-court paint. On clay, use the material and marking method intended for that court.
How far is the service line from the baseline?
The service line is 21 feet from the net, and the baseline is 39 feet from the net. That puts the service line 18 feet from the baseline.
Can I mark a singles court inside a doubles court?
Yes. Keep the 78-foot length, then mark singles sidelines 4.5 feet inside the doubles sidelines on both sides. The resulting singles court is 27 feet wide.
Do court dimensions include the painted lines?
Yes. Measure the playing area to the outer edge of its boundary lines. Measuring from inner edge to inner edge would leave the court undersized.
Final Thoughts
Accurate marking comes down to patient measuring: square the outer rectangle, confirm the diagonals, and then place the service lines and center marks from fixed reference points. Use a marking material suited to the surface, and check every measurement before making permanent lines. A few careful checks at the start make for a court that plays cleanly from the first serve.
