# GTrace - G-Meter & Logger — G-force traces for track days

> Real-time G-force meter and driving analysis tool for enthusiasts. (iPhone/iPad app by YUJI IKEDA.)

- Source: https://appshunter.io/ios/app/gtrace-g-meter-and-logger/id6751810264 (this page in markdown: same URL + `.md`)
- Developer: [YUJI IKEDA](https://appshunter.io/developer/1835230135)
- Category: Navigation, Sports
- Price: $0.99 (on sale, was $2.99)
- Age rating: 4+
- Requires: iOS 15.6 · 39 MB
- Languages: American English, Japanese
- Released: 2025-09-10
- Data updated: 2026-08-31
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/gtrace-g-meter-and-logger/id6751810264/reviews.md

## What is GTrace?

Track day or mountain road, every G you used stays on record.

GTrace turns your iPhone into a real G-meter. It draws the lateral and longitudinal G-forces from your cornering, braking and throttle as a live trace, then lets you replay the run against the map, your footage or the graphs.

One-time purchase. No subscription, no in-app purchases.


WHILE YOU DRIVE

- Live G-G diagram, lateral and longitudinal G shown together
- Trailing trace, with peak lateral and longitudinal G held on screen
- Jerk shown as a crosshair, so you can see how smoothly you transfer load
- Speed readout, switchable between km/h and mph
- Audible alert when you exceed your chosen G threshold
- Comfort and Sport modes with separate display ranges for street and track
- Three display layouts: standard, info + speed, and video preview
- Phone holder mode, so a vertically mounted phone still reads longitudinal G correctly


MEASUREMENT

- Gravity component removed to isolate true vehicle acceleration
- 2nd-order Butterworth IIR low-pass filter with adjustable cutoff frequency
- Configurable sampling rate
- Axis inversion, so mounting orientation doesn't matter


AFTER THE RUN

- G-G heat map showing which part of the friction circle you actually used, so you can see the balance between cornering, braking and acceleration at a glance
- Synced playback: G-G + map, G-G + video, G-G + acceleration graph, or map + graph, at adjustable playback speed
- Time-series graphs for longitudinal G, lateral G, longitudinal jerk, lateral jerk and speed
- GPS trace drawn on a map, with top and average speed


RECORD AND SHARE

- Voice recording, synced to the acceleration data for commentary and notes
- Video recording with audio, played back with the G-G trace overlaid
- CSV export for spreadsheets or your own analysis tools
- Native binary format (.ggx) import and export, for backups and moving data between devices


WHO IT'S FOR

- Track day, sports driving and time attack enthusiasts
- Drivers working on their technique on mountain roads
- Anyone chasing smoother, more passenger-friendly load transfer
- Motorsport competitors who want their practice data kept
- Anyone who wants their car's behaviour in numbers


English and Japanese. iPhone only, iOS 15.6 or later.

Note: measurements use the iPhone's built-in accelerometer and gyroscope. Mount the phone firmly in the vehicle for accurate readings.
Note: GPS trace and speed recording require location permission.
Note: this app does not include lap timing.

## Key features

- Real-time G-force display
- Driving trajectory visualization
- Session recording and data export
- GPS route recording
- Voice memo function
- Sensitivity adjustment and calibration

## Chart rankings

- #153 in Top Paid · Navigation (US App Store)

## Recent user reviews (2 of 2)

All indexed reviews: https://appshunter.io/ios/app/gtrace-g-meter-and-logger/id6751810264/reviews.md

### 5/5 — amazing G force app

*2026-01-30*

Don't be confused by the Japanese name. It supports English.

### 5/5 — まさに求めていたアプリ

*2025-09-11*

長年こういうアプリが欲しいと思っていました。これを使ってより良いドライビングテクニックを身につけます！

## Frequently asked questions about GTrace

### What is G-G Diagram?

G-G Diagram is a professional application that turns your smartphone into a high-precision G-meter. It measures and visualizes longitudinal and lateral acceleration (G-forces) in real-time during driving.

### What driving data does G-G Diagram measure?

G-G Diagram measures and analyzes longitudinal G, lateral G, cornering, braking, and throttle operation. It also supports accelerometer and gyrometer sensor data.

### Can I record my driving sessions with G-G Diagram?

Yes, G-G Diagram allows you to record, save, and export your driving sessions. It also includes GPS location-based trajectory and route recording.

### Does G-G Diagram support multiple languages?

Yes, G-G Diagram offers multi-language support, including Japanese and English, to cater to a wider range of users.

### How much does G-G Diagram cost?

G-G Diagram is a paid application priced at $0.99.

### What devices is G-G Diagram compatible with?

G-G Diagram is supported on iPhone and iPod devices.

### How often is G-G Diagram updated?

The latest version of G-G Diagram is 2.0.0, and it was last updated on January 6, 2026. This indicates a relatively recent update.

### Does G-G Diagram have ads?

No, G-G Diagram does not contain advertisements.

## Version history (last 5 releases)

### 2.2.1 — 2026-08-28

Landscape orientation is back, for use with a car mount.

- Restored landscape display on iPhone
- Fixed the Save button being hidden when saving a recording in landscape

### 2.2.0 — 2026-08-17

The app is now called GTrace, previously G-G Diagram. All features and your saved recordings are unchanged.

- Japanese is now listed as a supported language
- Unified the app name across the app and the App Store

### 2.1.0 — 2026-06-06

- Added mph speed display support
- Refreshed the design

### 2.0.0 — 2026-01-06

Now supports driving video recording.

### 1.2.0 — 2025-09-16

- Minor bug fixes
- Added speed display feature

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## More apps by YUJI IKEDA

- [Simple Assets: Money Manager](https://appshunter.io/ios/app/simple-assets-money-manager/id6751455631)

All apps by YUJI IKEDA: https://appshunter.io/developer/1835230135

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-31.*