Joystick Test: Circularity, Range and Dead Zone

Push one stick all the way out and roll it slowly around the edge: the tester draws the path in teal, marks the farthest point it saw at each of 36 angles, and reports range, circularity error and an estimated dead zone for that stick. A circularity error under 8% with a range near 100% means the stick travels fully and evenly in every direction; over 15% means the travel is uneven or clipped.

This is the test to run when a character walks slower in one direction, a camera turns unevenly, a diagonal input does not register, or a replacement stick module feels different from the original. It complements the stick drift test, which looks at the stick at rest rather than at the edge, and the full gamepad tester on the home page, which checks buttons and triggers.

How to run the joystick test

1. Connect the controller over USB or Bluetooth and press any button once so the browser reports it. The status line shows the controller's name and its button and axis count.
2. Push the left stick all the way to the edge and roll it slowly around the full circle two or three times. Slow is important: a fast flick skips angles and the tester needs at least 33 of the 36 angles before it will score the stick.
3. Watch the dots that appear at the edge of the trace. Teal dots sit between 85% and 105% of full travel; a red dot marks an angle where the stick stopped short or went past the expected edge.
4. Do the same with the right stick. The two panels are independent, so a problem on one side does not change the other side's numbers.
5. For the dead zone estimate, push a stick slowly from centre straight outward once. Press Clear traces to wipe both panels and start again, for example after swapping to another controller.

The orange dot is the live position of the stick. The outer solid ring is 100% travel, the dashed inner ring is 80%, and the dashed square shows where a stick that reports both axes at full would land in each corner.

What is circularity error?

Circularity error measures how evenly the stick reaches its edge around the full circle. The tester keeps the largest radius it has seen in each 10-degree slot and calculates how much those 36 radii vary relative to their average. A stick whose edge is the same distance from centre at every angle scores near 0%; a stick that reaches full travel on the left but stops at 70% on the right scores high.

A low circularity error does not by itself mean the stick is healthy. If every angle reaches only 80%, the error is tiny but the range is poor, so always read the two numbers together. The verdict under each panel is based on circularity only: Round, full travel under 8%, Usable, slightly uneven under 15%, Uneven or clipped from 15% up.

What the joystick test numbers mean

Range tells you whether the stick can still deliver a full input. Games map 100% stick to full run speed or maximum turn rate, so a stick that tops out at 85% makes you slower than everyone else without feeling broken. Circularity error tells you whether that limit is the same in every direction. Now is the same pair of values the raw data grid shows on the home page, rounded to two decimals, and is useful for checking a single direction by hand.

Why does a stick trace look square, flat or short?

The stick on an Xbox, PlayStation or Switch controller swings inside a round gate, so the physical limit is a circle. But the controller reads X and Y with two separate sensors, and pushing into a corner can bring both close to full, which is why a trace can look slightly squarish on a brand-new controller. Many controllers clamp the combined value in firmware; whether and how much depends on the model.

A trace that is flat on one side only is different. The stick is reaching the gate but the sensor on that axis is not reading full travel, which points to a worn potentiometer track, a module that has shifted in its housing after a drop, or a calibration stored in the controller that no longer matches the hardware. A trace that is round but short all the way around points to a replacement module with a smaller electrical range than the original, or to a controller whose stored calibration expects more travel than the module can give.

Joystick test vs stick drift test

The two tests answer different questions. This page checks the stick at the edge of travel: range, roundness and how far from centre the stick has to move before the controller reports it. The stick drift test checks the stick at rest: with your hands off for ten seconds, how far from centre does it sit, and how steady is that reading.

A stick can pass one and fail the other. A worn stick often drifts at rest while still reaching the edge cleanly; a replacement module often sits perfectly at centre while never reaching 100%. When a controller feels wrong and you are not sure why, run both and read the numbers side by side before you decide between cleaning, calibrating or replacing.

Controller dead zone test: what the estimate is and is not

The dead zone figure here is a rough estimate of where the controller's own reporting starts, not the dead zone a game applies. The tester records the smallest reading it has seen once a stick is clearly away from centre, so pushing slowly from centre outward gives a lower, more honest figure than a fast flick. Treat it as an indicator that the controller is reporting small movements at all, not as a number to copy into a game's settings.

Games and platform layers add their own dead zone on top, and that is the one you actually feel. Steam Input, DS4Windows and most console games let you set it; if a stick drifts slightly, the stick drift test suggests the dead zone value that would hide it. If you are checking a PlayStation controller, the PS5 controller test and PS4 controller test explain which readings those pads expose to a browser and which they keep to themselves.

What the joystick test cannot see

The test reads the two axis values the browser receives and nothing else. It cannot see the physical position of the stick, so it cannot tell whether a short range is the module or a calibration offset stored in the controller. It also cannot see a dead zone or sensitivity curve applied by the game, Steam Input or a console profile, because those are applied after the controller has reported.

Results also depend on how the controller is connected. Some pads report a slightly different range over Bluetooth than over USB, and some switch to a different mapping with different axis scaling when a mode switch is flipped. If the numbers look strange, press Clear traces, plug in a cable, and roll the stick again before you conclude anything about the hardware.

Related tests

Run the stick drift test for the hands-off measurement at centre, go back to the gamepad tester to check every button and trigger, and see the PS5 controller test or the PS4 controller test for DualSense and DualShock 4 specifics, including stick calibration from the browser.