78 feet from baseline to baseline.
A tennis court from baseline to net is 39 feet, so 39+39 = 78 and 78/3 equals 26 yards.
From the baseline to the net, a tennis court is about 21 feet. This gives the person plenty of space to jump around in.
Tennis court lines are referred to as the "baseline", "service line", "singles line", "doubles line", and "center line". There is also a small "center mark" protruding from the court in the middle of each baseline.
The length for a standard tennis court is 78 feet long, meaning there is 39 feet from the net to a baseline.
36' x 78'
From baseline to baseline and from alley to alley, a tennis court measures 78 feet by 36 feet. This does not include the extra area beyond the lines where the players run. For more specific measurements, check this link for a detailed tennis court diagram: http://www.prosportsofficialteamsites.com/Tennis_Nova_Sports_Court_novasports.gif
If you are standing on the baseline and looking at the net, the right-hand side of the tennis court is called the deuce side.
It is the 12" mark at the 1/2-way point of the baseline used to distinguish 2 halves (and service boxes) of a tennis court; short mark that bisects baseline.
If you are standing on the baseline and looking at the net, the deuce side of the court is on the right.