Launch Timer
0–60, quarter mile and braking, timed by your iPhone
Launch Timer combines the iPhone's GPS with its motion sensors, 100 readings a second, to time launches, rolling pulls and stops — and shows a live dashboard on your car's screen.
Timing a run
- Mount the phone firmly. Any angle works, but it must not move during the run.
- Stop, and wait for Ready.
- Launch. The clock starts on the first movement and stops when you lift.
- For braking, get above 60 mph (100 km/h) and brake to a full stop.
Only time runs on a closed course or drag strip.
Car screen
Open hakob17.github.io/launchtimer/car in the car's browser (Tesla or any car with a web browser), and enter the pairing code from the app's Car screen tab.
Accuracy
On a flat, straight road with a clear view of the sky and a firmly mounted phone, times are typically within a tenth of a second. Tunnels, tall buildings, a loose mount and slopes make them less accurate; the app shows the slope of each run.
The 1-ft rollout setting starts the clock after the car has rolled one foot, as drag strips and most magazines do. It makes times about 0.2–0.3 s quicker.