Why this page exists
Measuring a net with a racket tells you the truth about the net and nothing about the court. Stand at the net line, stand a racket on the ground, and the cord sits exactly where the rules say it should: 0.914 m at the centre, 1.07 m at the posts.
Then you walk back to your baseline and the net looks far higher than it has any right to. Many courts are built to shed water, sloping gently away from the net line down to both baselines. The net is still correct — its height is measured from the ground directly beneath it — but your eyes are now lower than the ground it was measured from, so the cord covers much more of the far court than it would on a flat court.
That is what this page is for: checking it with your eyes instead of a tape measure. Set your height, stand where you normally stand, and compare what the cord hides against a reference you can actually see — someone standing on the far baseline.
Stand on the court
Drag inside the view to look around. Everything is at true scale, so the only things that change what you see are where you stand and how tall you are.
The science behind
Your eyes sit at a height h above the court under your feet. The sight line that matters is the one grazing the top of the cord: everything on the far court below that line is behind the net, visible only through the mesh. The line meets the ground this far past the net:
Case 1. A flat court
The line that matters is a single straight one: from your eye, grazing the cord, on down to the ground. Being one line, it cuts the two shaded triangles in the drawing — and they are similar, which is Thales’ intercept theorem: the line crosses two parallels, your eye level and the ground.
Case 2. A sloping court
Most courts are laid to shed water, falling away from the net line to both baselines. The slope leaves the net line itself in place, so that is where we measure from. Two things change at once, not one: you stand on ground that is lower, and the far court no longer lies flat — so the two triangles stop being similar and Thales no longer applies. Instead we write down both lines and find where they cross. We do it for the one stance this page is about — you on your own baseline, the full L from the net — because that is where it is simplest and where it bites hardest. Throughout, u is any distance past the net, L is the 11.885 m from the net to a baseline, and s is the drop over that distance, negative when the baselines sit low. (In the drawing you are on that baseline. The answer lands well past the far baseline — off the court entirely, which is the point: the dashed stretch is the surface carried on beyond it, so the ring has somewhere to sit.)