Controller circularity test

How to run the circularity test

1. Connect the controller by cable or Bluetooth and press any button so the browser can see it. If several are connected, choose one under Controller.
2. Push one stick to its edge and rotate it slowly, pressing gently against the outer gate, for several full turns in both directions.
3. Keep going until the result appears. It is shown once at least 95% of the directions have been covered; before that the page tells you how many are done.
4. Do the same with the other stick. Clear shape starts again, for example after a calibration.

How the result is calculated

The circle is divided into 72 directions of 5° each. For each direction the page keeps the largest distance from the centre the stick reached, where 1.0 is the edge of the ring; readings less than halfway out are ignored. The average error is the mean of |largest distance − 1| over the directions covered, shown as a percentage. 0% means the stick reached exactly the edge in every direction.

• Shape inside the ring in some directions: the stick does not report full output there.
• Shape outside the ring, usually at the diagonals: the stick reports more than 1.0 in total there, typical of a square or octagonal output. Each axis is limited to −1…1, so the shape cannot go beyond the corners of that square.

Reading the result

• There is no universal pass mark. Many controllers have a deliberately square-ish or octagonal gate or firmware scaling, so a high percentage can simply reflect the design.
• What deserves attention is one direction falling clearly short of the others, a dent in the shape. That can come from wear, debris or calibration, and in games it means you cannot reach full speed or full turn in that direction.
• Compare the left and right stick of the same controller, and the result before and after a calibration. Rotate slowly: fast spins skip directions and give jagged shapes.
• Circularity says nothing about drift or about the health of Hall-effect or TMR sensors. For movement at rest use the stick drift test; to set a centre deadzone use the controller deadzone test.

Limits

The browser sees stick values after the operating system, driver and any remapping software such as Steam Input. Games apply their own deadzones and response curves, so what you see in a game can differ. The page reads the first four axes as the left and right stick; if the gamepad tester reports non-standard mapping for your controller, those axes may not be the sticks. Nothing on this page calibrates or changes the controller.