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Mouse Diagnostic

DPI Analyzer & Calculator

Calculate your true gaming mouse DPI (CPI) and sensor deviation online for free. Measure physical mousepad movement against raw pixel counts accurately.

Move mouse horizontally across a physical ruler by your selected target distance.

DRAG MOUSE HORIZONTALLY ACROSS RULER DISTANCE 0 DPI 0 pixels traversed

DPI Deviation & Standard Presets

Compare your measured true DPI against standard factory steps (400, 800, 1600, 3200 DPI):

< 2.5% Deviation (High Accuracy)

Sensor lens height and skate calibration are spot on. Muscle memory translates 1:1 to in-game crosshair movement.

2.6% – 6.0% Deviation (Moderate)

Common with aftermarket thick skates. Easily compensated by fine-tuning in-game sensitivity decimal points.

> 6.0% Deviation (High Skew)

Significant sensor height mismatch or firmware scaling bug. Re-calibrate Lift-Off Distance (LOD) in driver.

How to Get Started

Just three steps to run a complete controller test and understand your controller's health status.

01

Connect Controller

Connect your controller to your computer via USB cable or Bluetooth. If the browser doesn't respond, press any button on the controller to activate the connection.

02

Button Detection

Press each button in the visual interface and confirm the corresponding area lights up on screen. This helps troubleshoot unresponsive or double-clicking buttons.

03

Sticks & Vibration

Rotate the sticks to check linearity and drift issues; click the vibration test button to feel if the left and right motor feedback is working properly.

What would you like to do next?

Select a diagnostic calibration suite, deadzone analyzer, or high-frequency overclock tool.

Fix

Repair & Calibration

Calibrate zero-point offsets or follow step-by-step repair guides.

WebHID Calibration
Optimize

Game Deadzones

Calculate exact radial vs axial deadzone overlays for Fortnite, Apex, & COD.

Deadzone Calculator
Telemetry

Overclock & Circularity

Verify browser-observed update timing Hz stability and statistical circularity grades.

Hz & Circularity Tools

Need to check mouse report rate?

Measure your optical sensor's USB polling rate up to 8000Hz (8KHz).

Polling Rate Test CPS Speed Test

Related Diagnostic Tools

Polling Rate Checker

Measure mouse Hz frequency.

Click Latency

Measure click response delay.

CPS Test

Test clicks per second speed.

The Science of Counts Per Inch (CPI) & Sensor Deviation

Modern optical gaming mouse sensors (such as the PixArt PAW3950, PAW3395, and Logitech HERO 2) capture microscopic surface images at up to 20,000 frames per second. By comparing microscopic surface texture shifts between successive CMOS frames, the sensor calculates physical displacement in discrete Counts.

Why Higher DPI Lowers Initial Motion Latency

At 400 DPI, your mouse must physically move 1/400th of an inch (0.0635 mm) before the sensor registers a single count packet. At 1600 DPI, movement is registered after just 1/1600th of an inch (0.0158 mm)—cutting initial motion detection latency by up to 2ms to 4ms in fast reaction flicks.

Measuring True DPI vs. Nominal Manufacturer Settings

A mouse configured to 800 DPI in software often operates at 780 DPI or 830 DPI in reality. By measuring raw counts across a physically measured 2-inch or 5cm ruler travel, this tool provides the exact scaling factor to match your true sensitivity across all competitive games.

Controller Hardware Glossary & Tips

Stick Drift & Deadzones

Stick drift occurs when analog sticks register input without being touched. This is typically caused by physical wear in traditional carbon-film potentiometers. A deadzone is a software-level threshold (e.g., 5-10%) applied to ignore these microscopic false inputs.

Hall Effect Sensors

Unlike traditional ALPS potentiometers, Hall Effect modules use magnetic fields to measure stick position. Because there is no physical contact or friction between the internal components, they are virtually immune to wear-induced stick drift, drastically extending the controller's lifespan.

Polling Rate (Hz) & Input Latency

Polling rate is how often your controller sends data to your device, measured in Hertz (Hz). A standard Bluetooth connection yields around 125Hz (8ms latency). Overclocking or using a wired USB connection can push this to 500Hz-1000Hz (1ms-2ms latency), critical for competitive gaming.

Circularity Error

When you rotate a joystick along its outer edge, a perfect module should trace a mathematically perfect circle. Circularity error measures the deviation from this perfect circle. High deviations (>15%) can result in uneven diagonal movement speeds in FPS games.

Frequently Asked Questions

Everything you need to know about testing your controller.

How do I calculate my true mouse DPI online?

Select your physical measurement distance above (e.g. 2 inches / 5 cm), place your mouse at the zero-mark on a physical ruler, and drag your mouse horizontally across that exact distance. The analyzer divides the raw hardware movement counts (deltaX) by physical inches to calculate true DPI.

What is the difference between DPI and CPI in gaming mice?

While commonly called DPI (Dots Per Inch), the technically accurate term for optical mouse sensors is CPI (Counts Per Inch). It measures how many coordinate displacement samples the sensor CMOS camera registers for every 1 inch of physical movement across your mousepad.

What causes mouse DPI deviation (e.g., 800 DPI measuring as 840 DPI)?

DPI deviation is caused by slight manufacturing variations in sensor lens height, mouse skate/feet thickness (thick PTFE or glass skates lift the sensor slightly further from the surface), and pad weave texture.

What is eDPI and how is it calculated in Valorant and Counter-Strike 2?

eDPI (Effective DPI) standardizes true aim sensitivity across players: eDPI = True Mouse DPI &times; In-Game Sensitivity. For example, 800 DPI &times; 0.35 in Valorant equals 280 eDPI.

Is 1600 DPI better than 400 DPI or 800 DPI?

Yes! Higher sensor DPI (like 1600 or 3200 DPI combined with lowered in-game sensitivity) reduces input latency by up to 2ms to 3ms because the optical sensor detects the start of physical hand movement faster.

How this test works & its limits
  • This test reads your controller through the browser's standard Gamepad API — no drivers, no installs, nothing leaves your device.
  • Readings depend on connection mode: Bluetooth reports at lower rates than USB. Compare like-for-like (wired vs wired).
  • We measure the input reaching the browser — display lag and game-engine queues are outside this test's view.
  • A clean reading now does not guarantee no drift in-game: deadzones differ per game, and wear develops over time. Use the Drift Timeline to track yours.
  • This is a diagnostic, not a hardware-lab certification. For repair or RMA decisions, confirm with a second run or second tool.
Read the full methodology
100% Client-Side

All Gamepad API data stays in your browser. Zero tracking or data collection.

Instant Results

No downloads, plugins, or software installation needed. Works instantly.

Free Forever

No paywalls, subscription requirements, or hidden usage limits.