CLOCKER

Clocker vs the Photo Finish app

Photo Finish is the closest thing to Clocker on the market, and the only competitor with independent peer-reviewed validation. The two differences that matter are how many phones you need and how many frames a second it sees.

The short version

	Clocker	Photo Finish
Detects start and finish	Yes	Yes
Manual frame marking	None	None
Devices needed for a sprint	One iPhone	Two minimum, one at each line
Detection frame rate	240 fps (0.004 s a frame)	30 fps (0.033 s a frame)
Android	No	Yes
Independent validation	Not yet published	Yes. Sensors, 2024
Several runners on the track	One at a time	One at a time
Price	$49/yr	Free tier; Pro about $54–60/yr

The two-device requirement

Photo Finish detects a runner crossing the line at the camera. To time a sprint you therefore need a camera at the start line and a camera at the finish line, paired together. Its own FAQ states a minimum of two devices, and the independent accuracy study ran every one of its test setups with paired start and finish phones.

That is a perfectly reasonable design. It is also two phones, two tripods, and a pairing step, at both ends of a track, before anyone runs.

Clocker gets the start from a different signal entirely: the starter covers the camera lens with a hand and takes it away, which is an unmistakable event in the footage at the finish line. One phone, one position, no pairing.

30 frames a second versus 240

Detection frame rate sets the floor on how precisely a crossing can be placed. At 30 fps a frame lasts 0.033 seconds; at 240 fps it lasts 0.004. For a nine-year-old improving by a tenth of a second across a season, that is the difference between a measurement and a rounding.

When Photo Finish is the better buy

It runs on Android, which Clocker does not. It has been independently validated in a peer-reviewed journal: the 2024 Sensors study found it within 0.012 s of dual-beam photocells at 10 m, while Clocker has published no equivalent study yet. And if you already own two phones and a pair of tripods, its split timing over multiple points is something Clocker does not attempt.

What they share

Neither handles a pack. Photo Finish's documentation notes that other runners on the track break its detection, and Clocker times one runner per rep for the same underlying reason: a gate that is blocked cannot tell you who blocked it. Both are tools for timing an individual athlete's rep, not for scoring a race.

Try it

Clocker times a sprint from one iPhone at 240 frames a second. It finds the start and the finish itself, and shows you the frames either side of each mark so you can check the number rather than trust it.

SEE HOW IT WORKS