How We Detect Stick Drift
We sample each stick's radial resting magnitude for 5 seconds while the controller sits untouched, then compare the observed maximum with GPADLAB's site-defined bands. Under 0.05 is our healthy reference, 0.05 to 0.15 indicates increasing center offset, and 0.15 or higher is our severe-drift band for further investigation.
What How We Detect Stick Drift means
The exact detection algorithm
Every threshold below is a constant in the shipped code: DRIFT_THRESHOLD = 0.05, WARN_THRESHOLD = 0.15, SAMPLE_DURATION_MS = 5000. The calculation is exact, while the interpretation of 0.05 and 0.15 is GPADLAB's benchmark policy rather than a universal hardware-failure standard.
- 01
Read both sticks per frame
On each requestAnimationFrame tick, the tester reads pad.axes[0] and pad.axes[1] for the left stick, pad.axes[2] and pad.axes[3] for the right. These are the standard Gamepad API axis positions in the range -1.0 to 1.0 relative to each stick's center.
- 02
Compute radial magnitude
For each stick, we compute magnitude = sqrt(x² + y²) - the Euclidean distance from center in the axis plane. This matters because a stick can drift diagonally: an axis-by-axis check would miss a stick registering (0.04, 0.04) which has real magnitude 0.057. We measure the actual radial displacement, not axis-by-axis clip.
- 03
Track maximum during rest window
During the 5-second sample window, we hold the maximum magnitude observed for each stick. We use the max - not the mean - because drift often presents as intermittent spikes rather than constant offset. A stick that rests at 0.02 but spikes to 0.12 once per second is drifting, and only max-tracking catches it.
- 04
5-second untouched window
The window runs for exactly 5,000 milliseconds. The instruction - place the controller on a flat surface and do not touch it - is the crux of methodology validity. If the user's hand disturbs either stick during the window, the measurement becomes meaningless. Five seconds is short enough to complete without fidgeting but long enough to observe intermittent drift spikes.
- 05
Verdict from the worse stick
At window close, we take the maximum of leftMax and rightMax and compare it with the tester's three bands: under 0.05 passes GPADLAB's healthy reference, 0.05 to 0.15 is the middle drift band, and 0.15 or higher is the tester's fail band. The worse stick determines this GPADLAB verdict.
How We Detect Stick Drift drift verdict thresholds
The three-band scale below uses the Gamepad API's normalized -1.0 to 1.0 axis range. A magnitude of 0.05 is about 5% of full-scale axis deflection and serves as GPADLAB's healthy reference point. Games can use different deadzones and response curves, so these bands should not be treated as universal playability limits.
| Max radial magnitude at rest | Verdict | Meaning |
|---|---|---|
| < 0.05 | Healthy | Within GPADLAB's healthy reference band and worth full points in the Controller Health Score drift stage. A game with a very small or custom deadzone can still expose behavior differently. |
| 0.05 - 0.10 | Mild drift | Observed center offset above GPADLAB's healthy band. Games with smaller deadzones may expose it sooner; retest and consider calibration or deadzone tuning where appropriate. |
| 0.10 - 0.15 | Noticeable drift | Larger observed center offset in GPADLAB's intermediate scoring band. Whether it produces visible movement depends on the game's deadzone and input processing; cleaning, recalibration, or hardware diagnosis may be worth considering. |
| ≥ 0.15 | Significant drift | GPADLAB's severe-drift band and faulty-severity scoring range. Investigate calibration, contamination, mechanics, firmware, and stick hardware; persistent severe offset can justify repair or replacement, but this number alone does not identify the physical cause. |
DRIFT_THRESHOLD (0.05) and WARN_THRESHOLD (0.15) are hardcoded in StickDriftTester.tsx as GPADLAB verdict thresholds. The scoring library scoreStickDrift() adds an intermediate 0.10 band for finer point calibration. These constants define GPADLAB's benchmark behavior, not universal controller-industry failure limits.
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How We Detect Stick Drift questions
Because the measurement is only meaningful when the sticks are truly at rest. Holding the controller inevitably applies subtle pressure through the grip - enough to nudge the sticks by 0.01 to 0.03 on some designs. That's the same order of magnitude as real drift. Placing the controller on a flat surface removes the confound entirely. If you must hold it, hold it as loosely as possible with your palms flat, no thumbs on the sticks.
For steady-state drift, five seconds catches almost everything. For intermittent drift - sticks that spike once every few seconds - a longer window catches more spikes. We chose 5 seconds because it's the minimum needed to observe most intermittent behavior while keeping the test brisk enough that users will actually complete it. If you suspect intermittent drift and the test passes, run it three times in a row: you'll catch a stick that spikes 20% of the time.
Because drift is a 2D phenomenon. A stick that reads (0.04, 0.04) has a radial magnitude of about 0.057 even though neither individual axis exceeds 0.05. Using sqrt(x² + y²) captures combined X/Y displacement. Games may use radial, axial, hybrid, or custom deadzone processing, so GPADLAB's radial method should not be mistaken for every game's implementation.
0.05 is GPADLAB's chosen healthy reference on the normalized Gamepad API scale. It leaves room for small center noise while keeping the benchmark sensitive to visible offset. It is not a universal game setting: some titles use smaller or larger deadzones, custom response curves, or user-configurable values, so gameplay impact must be checked separately.
0.15 is GPADLAB's severe-drift threshold and matches the fault band used by scoreStickDrift(). At that level the measured center offset is large enough to justify further diagnosis, but it is not a universal replacement threshold or a clinical industry standard. Recalibration, cleaning, mechanical inspection, firmware checks, or replacement may be appropriate depending on the controller and symptoms.
Because that's how the controller feels to the player. A DualSense with a pristine right stick and a drifting left stick is a drifting controller - you can't just play half the game with it. Averaging the two sticks would produce a misleadingly cheerful score. Taking the max of leftMax and rightMax reflects the actual gameplay experience: your best stick doesn't compensate for your worst.
Honest answer: the standalone Stick Drift Test uses radial magnitude sqrt(x² + y²), which is mathematically correct. The composite Controller Benchmark uses the simpler max(|axis0|, |axis1|) for pipeline consistency across its six stages. In practice both approaches produce very similar verdicts because drift almost always presents primarily on one axis; a purely diagonal drift is rare. The scoring library's scoreStickDrift() consumes whichever number the caller provides. If you want the most accurate drift number, use the standalone /tools/stick-drift-test - this is on the polish backlog to reconcile.
No - that's what the Hall Effect Checker is for, and even that tool infers rather than definitively identifies. This methodology measures behavior at rest. Hall effect sticks typically show axis noise floors around 0.005 to 0.015, potentiometer sticks around 0.010 to 0.030 - a subtle difference, not a clean signal. Sensor type inference from noise characteristics is unreliable; check the manufacturer spec or iFixit teardowns for a definitive answer.
Further reading
- Gamepad API - MDN Web Docs · MDN Web Docs
- Nintendo Joy-Con Repair Program · Nintendo Support
- Understanding Analog Stick Deadzones · Game Dev Stack Exchange