MotionShine01 / Ruler
You mark the distance
Lay a ruler beside the mouse. Start at 0 and slide to the 1 inch or 10 cm mark in a straight line.
Free tool
Mouse DPI test, measure it with a ruler.
Lay a ruler next to your mouse, click the pad, slide the mouse to the 1 inch or 10 cm mark and click again. The page counts the raw movement and divides it by the distance to give your DPI. Do a few runs to see the median and the spread. A browser cannot read the DPI setting, so this measures it. It needs a mouse or a trackpad.
Advanced
Leave this at 1. If a run on a mouse with a known DPI is always off by the same factor, such as 2, type that factor here.
Your runs
The movement is counted in this page. Nothing is sent anywhere.
How it measures
Counts over a distance you set.
02 / Counts
The page counts movement
The pointer is locked while you measure, so the page reads the mouse movement itself and not where the cursor lands.
03 / DPI
Counts divided by inches
DPI means counts per inch. Counts over the distance in inches gives your DPI. Do three runs and use the middle one.
Guide
How to test mouse DPI, step by step.
A mouse DPI test measures how many counts your mouse reports for every inch you move it. DPI stands for dots per inch, and for a mouse it is the sensor's resolution: at 800 DPI, sliding the mouse one inch sends 800 counts to the computer. This page measures it by asking you to slide the mouse a known distance on a ruler while it counts the raw movement. A browser cannot read the DPI setting from the mouse, so measuring is the only way to check it here.
How to use the mouse DPI test
- Pick a distance under Distance you will move the mouse. 1 inch is the starting choice. Longer distances are easier to measure well.
- Put a ruler on your desk next to the mouse and note where the mouse is at 0.
- Click the big pad. The page locks the pointer and the pad shows a count that goes up as you move.
- Slide the mouse in a straight line to your mark. Do not stop short or go past it.
- Click again, or press Escape. The page shows the DPI for that run.
- Do two or more runs. From three runs on, the big card shows the median, and the spread tells you how close the runs were.
The sum behind it
DPI is counts divided by inches. A 10 cm distance is 10 / 2.54 = 3.937 inches, because one inch is exactly 25.4 mm, as the NIST page on units of length states (checked 27 Oct 2026). If the page counts 6,299 over 10 cm, the DPI is 6,299 / 3.937 = 1,600. If you slide 2 inches and the page counts 1,600, the DPI is 800.
| Distance | Counts at 400 DPI | Counts at 800 DPI | Counts at 1600 DPI |
|---|---|---|---|
| 1 inch | 400 | 800 | 1,600 |
| 2 inches | 800 | 1,600 | 3,200 |
| 10 cm (3.937 in) | 1,575 | 3,150 | 6,299 |
Raw input and what it changes
The page asks the browser for unadjusted movement, which the Pointer Lock specification describes as movement that is not affected by platform changes (checked 27 Oct 2026). With it, pointer speed and acceleration in your system settings do not change the count, so the result is close to the sensor's own DPI. Not every browser accepts the request. The Raw input card says Yes or No after your first run. When it says No, the count includes your system's pointer speed, and the result will not match the sensor setting.
Why the number may not match the box
- Many mice report a DPI that is a little off their label. A reading within a few percent is normal.
- Moving along a curve or stopping short gives a lower number. Use a straight edge.
- Gaming mice with a high DPI can lose counts if the polling is slow. Try a lower setting to see if the number gets steadier.
- If every run is off by the same factor, such as 2, your system may report movement in scaled pixels. Type that factor in Advanced, under Count multiplier.
Limits of this test
It needs a mouse or a trackpad and a desktop browser. It cannot change your DPI, and it cannot show the polling rate. It tells you what your mouse does in a browser, which is what matters if you play browser games or use web tools.
To test the buttons of the same mouse, use the mouse click test. To practise with it, try the aim trainer.
Questions
Good to know.
How do I check my mouse DPI?
Put a ruler next to the mouse, click the pad, slide the mouse a set distance in a straight line, and click again. The page divides the counts by the inches.
Why does the page lock my pointer?
While the pointer is locked the browser sends raw movement and the cursor cannot hit the edge of the screen. That lets the page count a long slide exactly. Click again or press Escape to get your cursor back.
What does Raw input mean?
It says whether the browser skipped your system pointer speed and acceleration. Yes means the count is close to the mouse sensor. No means those settings are included.
Which distance is best?
The longer the slide, the smaller the error from where you start and stop. 4 inches or 10 cm is easier to measure well than 1 inch.
Is this the same as my in-game sensitivity?
No. DPI is the mouse hardware. A game multiplies it by its own sensitivity setting.
Can it read the DPI from my mouse software?
No. A web page cannot talk to the mouse driver. It can only count the movement it receives.
Does it work on a phone?
No. It needs a mouse or a trackpad, and a browser that supports pointer lock.
Is anything sent anywhere?
No. Your runs stay in this page and in this browser.
