← APP
ARC DRAG
●GPS
●ACC
●BARO
READY TO STAGE
REACTION
—
SECONDS
SPEED
0
MPH
60 FT
—
0 - 60 MPH
—
0 - 100 MPH
—
1/8 ET
—
1/8 TRAP
— MPH
1/4 ET
—
1/4 TRAP
— MPH
DENSITY ALT
— FT
G-FORCE
0.00x / 0.00y
DISTANCE
0
FEET FROM LAUNCH
PEAK G: 0.00
Tap ARM TREE when staged. Lights start in 0.75–1.75s (randomized).

Permissions

?
Motion sensors (accelerometer + gyro)
PENDING
?
Location (GPS for trap speed)
PENDING
Required for accurate timing. Granted permissions are remembered by your browser.

Tree Style

Tree
Pro = single amber → green @ 0.4s. Sportsman = 3 ambers @ 0.5s each → green @ 0.5s. RT Trainer = sportsman lights, tap REACTION on green; no sensors required.
Perfect light reference
Sportsman classic: 0.500 = perfect (RT measured from amber). Pro: 0.000 = perfect (RT measured from green). Foul = sub-zero.

Track

Distance
1/8 mile run captures up to 1/8 ET + trap. 1/4 captures all splits.
Track name
Optional label for run history.
Outside air temp
For density altitude calc. Leave blank to use phone reading.

Calibration

Mount orientation
Place phone in mount, hold car still, tap "Capture". Locks the vehicle reference frame so G-forces are measured forward/lateral correctly.
Accelerometer zero
Sample at rest to subtract bias. Auto-runs when stationary 2s.
NOT YET

Audio

Tree beeps
Audio cues for amber + green. Critical when phone is on dash.
Voice readout
Speak times after run completes.

Live sensor readings

About

BUDRIX Drag Timer uses your phone's accelerometer for sub-100ms launch detection, GPS for trap speed, and barometer for density altitude. All data stays on your phone. Export runs as JSON for analysis. Built for the Samsung Galaxy S24 Ultra and similar Android devices.

v0.1 demo · 2026-05-06