Compass Heading vs GPS Course: Why Direction Readings Differ
Learn the difference between the direction a phone points and the direction it is travelling, plus common causes of unstable heading.
A compass heading and a GPS course are not the same thing. Heading usually describes the direction the device or a compass points; course over ground describes the direction of movement. A phone held sideways can point east while moving north, so the two values can differ without either being wrong.
Device orientation and movement
Compass sensors estimate orientation using magnetic and motion sensors, where available. GPS course is usually derived from successive position fixes while the device moves. At rest, there may be no meaningful course because the phone has not travelled far enough to estimate a direction. A browser may not expose all orientation sensors or may require explicit permission.
Magnetic interference
Metal objects, vehicle structures, magnets, speakers and some cases can distort compass readings. Calibration prompts vary by device. If heading changes when the phone is rotated or moved near metal, move to a clear area and follow the operating system's calibration guidance rather than trying to correct the number manually.
Low-speed course noise
When movement is very slow, small position errors can be similar in size to the actual displacement. This makes direction estimates jump or rotate even when the path is nearly straight. At a standstill, a tracker should not imply that a noisy course is a reliable compass heading. Use direction as approximate context only.
Troubleshooting steps
Check sensor permissions, remove the phone from magnetic accessories, rotate it slowly in an open area, and compare the heading only while the device is moving steadily. If the browser does not provide a heading, the page should say so rather than inventing one. Do not use a web compass for safety-critical navigation.
Frequently asked questions
Why does course show zero while stopped?
Course needs meaningful movement between position fixes; a stationary device may have no reliable course.
Can a compass point differently from the route?
Yes. A compass follows device orientation, while course follows movement direction.
Technical references
These references explain the underlying browser and positioning concepts. They do not imply endorsement of this website.