How accurate can you measure serve speed from just a phone video?
My son and I are rec players who kept wondering how fast our serves actually are. Wingfield courts are rare and expensive around here, so I started doing the math myself — using the ball's flight time between contact and bounce, plus the court's known dimensions.
A few things I learned that surprised me: normal 30fps video works better than I expected — for typical rec-level serves the flight time is long enough that being one frame off only costs a few km/h. Slo-mo tightens it further, and it matters more the faster you serve. What mattered most, though, was camera position: filming from far away with the service box small in frame systematically underestimates speed.
Has anyone here tried something similar? Curious whether my numbers hold up against what others have measured.
Posted Aug 12, 2026, 10:49 AM UTC