G-Circle - G-Force Meter

G-Circle is an app that visualizes G-force in real time, logs it, and lets you replay it later. It shows longitudinal G (acceleration and braking) and lateral G (cornering) on an intuitive "acceleration circle," so you can grasp the motion at a glance.

■ Features

[Real-time G-force display]
See longitudinal and lateral G on the acceleration circle in real time, along with a trace of up to the last 30 seconds.

[Mounting-angle correction]
A standout feature of this app. You don't need to mount your phone perfectly level or facing forward. A simple two-step calibration corrects for the mounting angle and measures G in the vehicle's frame of reference.
- Stationary calibration: aligns the fore-aft axis while parked
- Forward-G calibration: aligns the lateral axis as you drive straight

[Logging]
Record longitudinal and lateral G during a drive, along with both the raw accelerometer values and the low-pass-filtered values. In addition to raw angular-velocity readings, you can also log yaw, roll and pitch angular velocity converted into the vehicle's frame of reference. GPS location and speed are logged too, and long sessions are split into files automatically. Useful not only for driving, but also for anyone who wants the raw acceleration and angular-velocity data itself.

[Replay and review]
Play back a recorded drive with the acceleration circle, graph and map all synced, so you can review exactly where and how much G occurred over time.

[Map display]
View your driving trace on an OpenStreetMap-based map. During replay, your position on the map stays in sync with the G-force.

[Seek during replay]
While replaying, tap a point on the route, or drag the graph left or right, to seek playback to that moment. The acceleration circle, graph and map all move in sync.

[Graphs]
Time-series graphs of longitudinal, lateral and total acceleration and speed, plus angular velocity for detailed analysis.

[G-responsive sound]
A sound feature whose pitch rises with G-force, so you can sense changes by ear without looking at the screen. The starting threshold and pitch steps are adjustable.

[CSV export]
Export your recorded data as CSV to analyze in spreadsheets or other tools.

[Customization]
Adjust the G value at the outermost ring, smoothing (low-pass filter), trace and graph duration, map size and more.

■ For
- Drivers who want an objective view of their own driving
- Anyone recording and analyzing track or winding-road runs
- Anyone who wants to measure and log acceleration or angular velocity, not just for driving

■ Notes
This app is a measurement aid. Always prioritize safe driving and do not operate the app while driving. Readings depend on your device's sensor accuracy and should be treated as reference values.

This app is free and supported by ads.