How the DPI tester works
DPI (more precisely CPI, counts per inch) is the number of movement steps a mouse sensor reports for every inch it travels. If you move a 1600 DPI mouse exactly one inch, the computer receives about 1600 counts. This DPI tester measures that directly: you move the mouse a distance you know, the page adds up the counts it receives, and divides one by the other.
When you press Start, the page locks the pointer so the cursor cannot hit the screen edge, and in Chrome and Edge it requests unadjusted movement. That gives the raw counts from the sensor, before Windows or macOS applies pointer speed or acceleration. The result is your real hardware DPI, not the speed your cursor happens to move at.
How to test mouse DPI step by step
- Lay a ruler or measuring tape flat on your mouse pad. A credit card (3.37 in / 8.56 cm) works too.
- Type the distance you will move into the Distance box and pick inches or cm. Longer distances give more accurate results; 3 inches or 10 cm is a good start.
- Line up the front edge of the mouse with the 0 mark.
- Press Start measuring. The cursor disappears; that is expected.
- Hold down the left button, move the mouse in a straight line until its front edge reaches the end mark, and release.
- The pass appears in the list. Press Start again and repeat two or three times. Press Esc any time to cancel.
Keep the mouse flat and do not lift it during a pass. Move at a steady, moderate speed: very fast flicks can exceed the sensor's tracking speed on cheaper mice and lower the count.
Reading your mouse DPI check
The Average DPI box shows the mean of all passes. The Nearest step box rounds it to the closest common DPI setting, which tells you which step the mouse is probably on. Compare it with the value in your mouse software:
| Deviation from the set DPI | What it means |
|---|---|
| Under 3% | Excellent. Typical of good gaming sensors, and also within measurement error. |
| 3–8% | Normal for most mice. Fine for everyday use; adjust in-game sensitivity if it bothers you. |
| 8–15% | The sensor runs noticeably fast or slow. Common on budget mice. |
| Over 15% | Check you are on the DPI step you think you are, then re-test on a different surface. |
Why DPI matters
Consistent aim between mice
If you switch to a new mouse and set it to the same DPI number, your aim can still feel different because one sensor reads 5% fast and the other 5% slow. Measuring both with a DPI tester and matching the actual values gives you the same feel.
Understanding eDPI
Players often compare effective sensitivity as eDPI: DPI multiplied by in-game sensitivity. 800 DPI at 0.5 sensitivity is 400 eDPI, the same as 400 DPI at 1.0. Using your measured DPI instead of the advertised number makes eDPI comparisons meaningful.
Desktop comfort
On 4K or ultra-wide monitors, a low DPI means a lot of hand movement to cross the screen. Knowing the real value helps you pick a step that reaches the edges without making small movements jittery.
DPI tester tips for accurate results
- Use a longer distance. A small mistake in where you stop matters less over 10 cm than over 2 cm.
- Average several passes. Throw away an obvious outlier and keep the rest.
- Move straight. The tester uses horizontal movement. The vertical drift is shown so you can see if you wandered.
- Turn off angle snapping and smoothing in the mouse software if possible; they can change counts slightly.
- Other browsers: in Firefox and Safari, set pointer speed to default and disable acceleration for a reliable mouse DPI checker result.
Want to know how often your mouse reports those counts? Try the polling rate test. To check the buttons and wheel, use the main mouse tester.