Compass Test: Check Phone Compass Heading & Sensor Online
Compass test online: live heading in degrees, smoothness tracking, and stability check for used-phone inspection before you buy.
Updated 2026-08-24
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Features
- Live compass with a rotating dial: the heading in degrees and one of eight direction labels update in real time as you turn the phone
- Smoothness tracking: rotate the phone 360° slowly and the tool grades the needle's follow (smooth, jittery, or broken) from the step size between consecutive readings
- Stability at rest: hold the phone still for 3 seconds and the drift window tells you whether the heading holds within 3° like a healthy sensor
- iOS permission flow: Safari requires an explicit tap before reading orientation, so iPhone users get a clear Enable Compass Access button instead of a silent dead page
- Used-phone inspection flow: rotate 360° for smooth tracking, hold still for low drift; these checks together catch a faulty compass sensor before you buy
- Eight-direction labels: North, Northeast, East, Southeast, South, Southwest, West, and Northwest update instantly as you turn
- Figure-eight calibration guide: the tool reminds you to recalibrate if readings look off, with step-by-step instructions
- No data leaves the device: orientation readings are processed in the browser and never transmitted
How to Use
- 1Open this page on your phone with Chrome (Android) or Safari (iOS), and tap Start Compass Test. On iPhone, tap Enable Compass Access first and Allow in the prompt.
- 2Hold the phone flat, screen up, and rotate it 360° slowly. The dial turns against the fixed needle and the heading readout follows.
- 3Check the heading number against a known direction: in the northern hemisphere the sun is roughly south at noon, or compare with a phone's built-in compass app.
- 4Watch the Smoothness card while rotating: smooth means the sensor tracks continuously. Jittery or broken grading during a slow rotation means readings drop out.
- 5Then hold the phone completely still for 3 seconds and check Stability: drift under 3° is healthy, more than that suggests calibration or sensor wear.
- 6Test a used phone before buying: run the rotation and still-hold checks, then verify the heading against a compass app or a known landmark direction.
- 7If readings are clearly wrong, calibrate the phone with a figure-eight motion (the system app prompts for it) and re-run the test.
- 8Compare two phones side by side with the same motions: a healthy phone tracks smoothly and stays within a few degrees of the other after settling.
Frequently Asked Questions
How does this compass test work?
The page reads the DeviceOrientationEvent, whose alpha value is the phone's heading around the vertical axis in degrees (0–360). On Android Chrome it streams without a prompt; on iOS Safari it needs one explicit tap because of Apple's motion permission rules.
Why doesn't my iPhone show the compass reading?
iOS requires an explicit user gesture before any website can read motion or orientation data. Tap Start Compass Test, then tap Enable Compass Access and choose Allow in the system prompt. If you previously denied it, re-enable motion access under Settings > Safari > Motion & Orientation Access. Older iOS versions (before 13) never expose orientation to websites at all.
Why does my compass reading jump around?
Jumpy readings usually mean magnetic interference or a faulty sensor. Move away from speakers, magnetic phone cases, and metal desks, then re-test. If the needle still jumps during a slow rotation, the smoothness card will grade it jittery or broken, which points to the sensor itself.
How do I calibrate my phone compass?
Most phones calibrate automatically when you move the device in a figure-eight pattern: hold the phone flat and trace a horizontal 8 shape in the air a few times until the compass app stops asking. Some Android phones calibrate faster when you rotate the phone around all three axes. After calibration, re-run this test; a healthy sensor should hold within 3° when still and track smoothly when rotated.
Why is my phone compass inaccurate?
Inaccuracy has three common causes, in order: magnetic interference from accessories (magnetic cases, car mounts, credit-card magnets), a stale calibration after a long journey or metal exposure, and a faulty sensor. Calibrate with a figure-eight motion and compare against a compass app. If the heading is off by the same angle everywhere after calibration, the sensor needs repair.
How do I check the compass on a used phone?
Run two checks: rotate the phone 360° slowly and confirm the needle tracks smoothly without jumps, then hold it still for 3 seconds and confirm drift stays under 3°. Then point the phone at a known direction (the sun at noon in the northern hemisphere, or a road you know runs north-south) and confirm the heading is within a few degrees.
Why does my heading stay the same when I turn the phone?
A heading that does not change while you rotate usually means the orientation events are not reaching the page: iOS permission was denied (re-enable under Settings > Safari > Motion & Orientation Access), the browser tab was backgrounded, or the sensor is genuinely stuck. Check the running state and the smoothness card; a healthy phone produces a new reading within a fraction of a second of movement.
How accurate is a phone compass?
A calibrated phone compass is typically accurate to within 2–5°, which is fine for orientation and navigation. Accuracy degrades with magnetic interference, nearby metal, and stale calibration. This tool grades the two failure modes separately: smoothness catches dropped readings during rotation, and the still-hold drift check catches slow error accumulation. Both should pass before you trust the heading.
Does airplane mode affect the compass test?
No. The compass is a passive sensor that works in airplane mode, just like the accelerometer and gyroscope. Airplane mode only disables radios, so you can run this test with the phone fully offline. The only requirement is that the browser is open on the page and, on iOS, that motion permission was granted.
My compass is off by 180 degrees, is the phone broken?
Not necessarily. A 180° error usually means the phone is being held upside down or the sensor reference changed after an update; recalibrating with a figure-eight motion usually fixes it. A constant offset of exactly 180° that survives calibration can also indicate a sensor driver quirk on some models. If the offset varies with direction and survives calibration, the sensor needs service.