Circularity Test

Quick start

1. 1
   Connect your controller. Plug it in over USB, or pair it over Bluetooth in your device settings first.
2. 2
   Press any button first. Browsers will not notice a controller until they see its first input.
3. 3
   Pick the stick you want to test. Then slowly roll it in one full, smooth circle, pushing right to the edge of its travel the whole way round.
4. 4
   Read the score once the trace closes. A second slow pass gives a steadier, more repeatable result.

Test your stick

How to read the results

The trace plot

The dashed circle and the square behind it are reference shapes only, drawn at the plot's full radius so you have something fixed to compare against. The solid orange line is your stick's actual recorded path, filled lightly so the overall shape is easy to see at a glance. A healthy stick traces a path that hugs close to the dashed circle the whole way round. A path that bulges out toward the corners and pulls in along the flat edges is hugging a square gate instead of a circular one.

Circularity score

This compares the area your traced shape actually covers against the area a perfect circle of the same average radius would cover, expressed as a percentage. A true circular gate scores close to 100. A square gate scores noticeably lower, typically somewhere in the area of 78 to 85 percent, since a square's corners reach further than a circle's edge does at the same average distance, which drags the shape away from a clean round path. This is a measurement of your stick's mechanical gate shape, not a judgement of the stick being faulty, since plenty of controllers are intentionally built with a square gate.

Gate shape detected

Once enough of the trace has been recorded, this gives a plain verdict, circular gate, square gate, or somewhere in between, based directly on the circularity score and how evenly the reach varies across the eight tracked directions. Knowing which one you have matters for understanding how your stick will behave at the diagonals specifically, covered in the section below.

Maximum reach

This tracks the single farthest point your stick has reported in each of eight directions since the last reset, shown as a percentage of the plot's full radius. On a circular gate, all eight numbers should sit close together. On a square gate, the four diagonal directions, up-right, down-right, down-left, up-left, will read noticeably higher than the four cardinal directions, since the stick physically travels further to reach a square corner than it does to reach the middle of a flat edge.

Why gate shape actually matters in play

A stick's gate is the physical boundary that limits how far it can move, and whether that boundary is round or square has a real, felt effect on diagonal precision. On a square gate, the diagonals require pushing further to reach maximum input than the cardinal directions do, which means a quick flick toward a corner can undershoot full deflection in a way the same motion toward a flat edge would not. On a circular gate, every direction reaches its maximum at the same distance from centre, so diagonal and cardinal inputs behave identically in terms of how far you need to push.

Neither shape is universally better, some players specifically prefer a square gate's more pronounced diagonal feel for certain genres, particularly fighting games where players are used to a similar feel from arcade sticks. The value of this test is knowing for certain which one your specific controller actually has, rather than guessing from feel alone, so you can account for it deliberately rather than being surprised by it mid match.

Getting a clean, repeatable trace

Move the stick slowly and deliberately rather than flicking quickly around the edge, since a fast pass can skip past parts of the boundary between recorded frames and leave gaps in the trace that throw off the score. Push firmly out to the stick's true mechanical limit throughout the circle rather than staying just inside it, since a trace drawn at less than full extension will read as a smaller, sometimes oddly shaped path that does not reflect the gate's real boundary. Running two or three full slow circles back to back, rather than judging from a single pass, gives a steadier and more trustworthy score, particularly near the edges where a single frame's noise has more visible effect on a tight circle.

Connecting by device

Windows and Mac

Plug in over USB, or pair over Bluetooth in your system settings first. Chrome, Edge, and Firefox all support the controller out of the box once it is paired.

Android phone and tablet

Pair the controller in your device's Bluetooth settings, then open this page in Chrome. Other Android browsers vary in their support.

iPhone and iPad

Pair an MFi or Bluetooth controller in Settings, then open this page in Safari. iOS has supported the same Gamepad API since version 14.5.

Linux

Plug in over USB or pair over Bluetooth, then use Chrome or Firefox. Some distributions need a one time udev rule for certain Bluetooth controllers to be recognised by the operating system at all. If the controller is not visible at the system level, it will not be visible here either.

Troubleshooting

The score seems to change a lot between attempts

This usually comes from inconsistent pressure against the gate's edge between passes. Push firmly to the true mechanical limit on every part of the circle rather than easing off in places, and try a slower, more even pace.

The traced shape looks lopsided rather than evenly square or round

A lopsided rather than symmetrical shape, especially one that bulges unevenly toward just one or two directions rather than all four corners equally, points toward mechanical wear or a stick slightly off centre in its housing rather than a manufactured gate shape, which is normally symmetrical by design.

Maximum reach numbers will not climb past a certain point in every direction

Confirm you are pushing the stick fully to its physical limit rather than a comfortable range short of it. If every direction caps at a similar, clearly reduced percentage even at full push, that points toward an outer deadzone being applied somewhere upstream rather than a gate shape issue.

Nothing happens when I connect a controller

Press a button first. Many browsers will not register a controller until they see its first input.