Circularity Test — stick gate shape checker
A controller circularity test measures how round your analog stick’s outer rim is. Our free browser-based tester reads stick coordinates via the Gamepad API while you rotate the stick at full deflection, samples 300+ points around the rim, and computes circularity error as a percentage. Hall-effect sticks score under 5%; healthy potentiometer sticks score 5–10%; worn sticks score 10–20%. The polar plot visualizes the actual gate shape so you can see octagonal wear, dead spots, and corner sticking.
How the circularity test works
Connect your controller
Plug in via USB or pair over Bluetooth. Press any button to expose the controller to the page. The tester reads the left stick’s X and Y axes through the Gamepad API.
Push the stick to full deflection
Hold the left stick pushed all the way out so it rides along the physical gate. The math only counts samples where the radius from center exceeds 0.85 — anything inside that ring is ignored.
Rotate continuously around the rim
Rotate the stick around the rim, both clockwise and counter-clockwise, for at least two full rotations. The live polar plot fills in a 36-wedge coverage fan so you can see which angles still need coverage.
Auto-complete on 95% coverage
The test finishes when the 36 angular buckets are 95% populated and at least 300 rim samples are captured. On a confident rotation this takes around 6–8 seconds. A 15-second timeout fires if coverage stalls.
Read the result
Circularity error is (max radius − min radius) divided by mean radius, expressed as a percentage. The polar plot overlays a verdict-colored hull on the trace so you can see exactly where the gate flattens, peaks, or sticks.
What the circularity error means
Circularity error is expressed as a percentage. Lower is better. The thresholds below assume a rounded-gate stick — controllers with octagonal physical gates (DualShock 3/4, Switch Pro) carry a 10–15% baseline by physical design and the result panel adjusts the copy automatically.
| Error % | Verdict | What It Means |
|---|---|---|
| 0–5% | Excellent | Hall-effect or premium-grade potentiometer stick. The gate is functionally circular and the sensor is reading uniformly across all angles. |
| 5–10% | Good | Healthy potentiometer stick within typical manufacturing tolerance. New DualSense, Xbox Series X, and 8BitDo Ultimate pads typically land here. |
| 10–20% | Worn | Stick shows wear in one or more sectors. Normal for sticks past 12–18 months of regular use. Octagonal-gate controllers can score here even when new — check the result panel for the gate-shape note. |
| > 20% | Severely Worn | Stick replacement recommended. At this error level, precise movement (FGC inputs, racing-sim steering, Smash tilts) becomes unreliable. Consider a Hall-effect upgrade or full module replacement. |
Compatible devices
The circularity test works with any controller that exposes an analog left stick. Octagonal-gate controllers are auto-detected for context-aware result copy:
Common repair guides
Related diagnostics
Circularity questions
Circularity error is a measurement of how round your analog stick’s outer rim is when you push it to full deflection and rotate around the gate. A perfect stick produces a perfect circle, scoring 0%. Real sticks show some deviation because of physical gate shape, sensor non-linearity, and wear. We express it as (max radius − min radius) divided by mean radius, multiplied by 100.
Fighting-game and Super Smash Bros. inputs depend on precise diagonal motions — quarter circles, half circles, dash dances, tilts. When a stick’s gate is worn or uneven, those diagonals don’t register reliably, causing dropped inputs and execution failures. A worn cardinal direction (up, down, left, right) reads at maximum value while diagonals fall short, scrambling motion inputs. Competitive players test circularity regularly to know when to replace sticks.
An octagonal physical gate is a stick housing with eight flat sides instead of a smooth circular bezel. DualShock 3, DualShock 4, and Switch Pro controllers all use octagonal gates. When you rotate the stick around the rim, the stick travels farther at each corner than along each flat side, producing a circularity error of roughly 10–15% even on a brand-new controller. This is normal, not wear. Our test detects these controllers and adjusts the result copy accordingly.
Hall-effect sticks routinely score under 5%, with premium pads like the GuliKit KK3 Max and 8BitDo Ultimate often measuring 2–3%. New potentiometer sticks score 5–10%. Sticks past 12–18 months of regular use score 10–15%. Anything above 20% indicates significant wear and affects gameplay. For octagonal-gate controllers, add 10% to each threshold.
The test measures the gate shape, so it needs samples from all 360 degrees of the rim. We bucket the rim into 36 angular wedges and complete only when 95% of those buckets are populated. A still stick or partial rotation gives no data to compute circularity. The live polar plot fills in a coverage fan as you rotate so you can see which angles still need attention.
Yes — these measure different failure modes. Stick drift is unwanted input when the stick is centered. Circularity error is uneven reach at the outer rim. A stick can have a perfect center (no drift) while its gate has worn flat in one direction. FGC players often see this in dash dance failures: drift is fine, but tilt-then-snap inputs miss because the gate has worn unevenly.
Yes, materially. Hall-effect sensors use magnetic fields instead of physical carbon strips, eliminating the uneven wear that causes potentiometer circularity error to grow over time. Hall sticks typically score 2–5% even after extensive use. The trade-off is cost — Hall-effect modules run roughly $15–30 versus $5–10 for potentiometer replacements.
First check whether your coverage was complete — the result panel shows angular coverage percentage. If coverage was below 90%, the hull may be drawn across an empty arc, inflating the error. Re-run the test and make sure to rotate in both directions for a full two rotations. If coverage was complete and error is still high, your stick is genuinely worn or your controller has an octagonal gate that wasn’t detected (older third-party pads sometimes copy the DualShock gate shape without a recognizable id).
How we measure circularity
Built on the Gamepad API. Rim sampling at radius > 0.85 with 36-bucket angular coverage gating. Circularity error computed as (max − min) / mean across rim samples. Methodology published by GPADLAB Engineering.
Run the full Controller Health Score
This test is one of six diagnostics in the composite score. See how your controller stacks up overall.
Run the Benchmark