How to time a 40-yard dash
A 40 time changes by tenths depending on who holds the watch and how the start is set up. For a number you can trust and compare, you need the right timer and the same setup every time.
Three ways to time it
A stopwatch
It's free, and it's off by a lot. In a study of Division II players, hand-timed 40s ran 0.31 s faster than electronic times on the same reps. Hand vs electronic timing explains why and how to convert.
Gates or lasers
A gate at the start and one at 40 yards gives you an electronic time. Add one at 10 yards for the split scouts care about, and you're at three gates. Amazon laser kits run about $150 to $450; branded systems from OVR, Dashr and Brower run $529 to $1,589 for two gates, at October 2026 prices. Laser timers for sprints.
A wearable
Sprintbrick is a sensor that clips to your waistband and one receiver that sits behind the start. The receiver measures the distance to the sensor 100 times a second, so one rep gives you your 10, 20, 30 and 40-yard splits and your top speed, with nothing on the field.
Setup that changes your time
Measure 40 yards with a tape: 120 feet, or 36.58 m. Painted football lines are close, but at 40-yard speeds every 3 inches of error is worth about a hundredth of a second.
Pick one start and stick to it. Haugen and Buchheit's review of sprint testing found that over 40 m, a three-point start triggered by hand release ran 0.17 s faster than a block start with a gun, and a standing start triggered by the first gate ran 0.27 s faster. With gates, how far you stand behind the first beam matters too: 1 m back instead of 0.5 m made 5-20 m times 0.06-0.08 s faster.
Write the setup down next to the time, because a 4.6 means little if you don't know how it was started.
How Sprintbrick starts the clock
Sprintbrick starts timing when the sensor on your lower back has moved 0.5 m from your set position. That's close to a first-movement start, and it's the part we're still working on. In our tests against OVR gates, segments after the first 10 m came within 50 ms of the gates every time. The first 10 m read 0.04 to 0.09 s slower than the gates in our latest session, so for now your splits after the first 10 m hold up and your full 40 may read a few hundredths slow until we finish the start work. The OVR comparison has the numbers.