How the joystick test works
Rotate each stick slowly against its outer edge, two or three full turns. The test splits the circle into 36 sectors of 10° and keeps the farthest point reached in each one. The orange shape that grows on the plot is the real range of your stick; the grey circle is a perfect range of 1.00.
When every sector has been visited, the test gives a verdict for each stick:
- Average reach: the mean distance at the edge. 1.00 means the stick reaches its full value.
- Weakest direction: the shortest reach, and where it is (top, bottom left…).
- Circularity error: how far, on average, the edge is from a perfect circle.
Reading the verdict
| Verdict | Numbers | What it means |
|---|---|---|
| Full, round range | error below 5 %, every direction above 0.90 | Full speed in every direction. |
| Slightly uneven range | error 5 to 12 %, or one direction between 0.80 and 0.90 | Usually invisible in game. Worth a check again in a few months. |
| Limited range | error above 12 %, or a direction below 0.80 | Full tilt is slow in that direction. Dust, a worn stick or a damaged module. |
A short range usually comes from dirt around the stick base or a worn potentiometer. Rotate the stick firmly a dozen times and test again: if the shape grows, it was dirt. Many games also let you set an outer deadzone, which treats 0.85 as full tilt and hides a slightly short stick.
All axes and buttons
Below the plots, every axis your device sends is listed with its value from −1.00 to 1.00, and every button by number. This is the view to use for anything that is not a standard gamepad: flight sticks, HOTAS throttles, pedals, arcade sticks, wheels, or a controller with a non-standard mapping. Move each control and check that its axis moves smoothly across the whole bar, without jumps.
An axis that jumps or flickers usually points to a dirty potentiometer. An axis that never reaches −1.00 or 1.00 needs calibrating in the device’s software or in Windows (joy.cpl).
Limits
The browser reports what the device and the operating system send, after any calibration they apply. Devices that need a vendor driver may show fewer axes than in their own software. Bluetooth can add small jumps. For the centre of the stick, use the stick drift test; to see every button on a diagram, use the controller tester.
Frequently asked questions
What is a good circularity error?
Below 5 %, the stick reaches the same distance in every direction. Between 5 and 12 %, the range is a little uneven, which rarely matters in games. Above 12 %, or below 0.80 in one direction, full tilt will feel different depending on the direction.
Why is my diagonal above 1.00?
Some controllers, often third-party ones, report a squarish range where the diagonals pass 1.00. The stick is not faulty, but the circularity error looks high. In that case, look at the weakest direction instead.
Does it work with a flight stick or a HOTAS?
Yes, if the device is a standard USB game controller. The list shows every axis (stick, twist, throttle, rudder) and every button by number. The range test uses the first two pairs of axes, so it maps the main stick.
How is this different from the drift test?
The drift test measures the stick at rest, in the centre. This test measures the edge: how far the stick can go in each direction. A stick can pass one and fail the other.
Updated October 26, 2026