Mouse DPI test. Counts per inch, measured.
A mouse's DPI setting is how many counts it reports per inch it moves. This test locks the pointer, asks for raw movement where the browser gives it, and counts while you move the mouse a distance you measured: along a ruler, or the long edge of a bank card. Three passes give a median and a spread, and the result is set against the DPI you chose.
One check · Your pace
Asks for: A mouse, and a ruler or a bank card. It runs in its own window and nothing leaves this page.
In short
Mouse DPI test: the answer first
A mouse DPI test counts what the mouse reports while you move it a measured distance. This one locks the pointer, asks for raw movement so the system's acceleration is left out, and divides the counts by the inches you moved. Three passes give a median and a spread.
Reading your result
- Raw or accelerated
- Raw movement is the mouse's own counts. Accelerated movement has passed through the system and may differ; the result says which you got.
- The spread
- Passes that disagree mean the distance or the line varied. Use a straight edge and stop exactly on the mark.
- Against your setting
- The difference from the DPI you set is the sensor's deviation plus your measuring error; a millimetre off over ten centimetres is one percent.
What it measures
Measured here, not assumed.
- Counts per inch
- The movement the browser hands the page while the pointer is locked, summed as a straight-line distance, over the inches you moved. Counts per inch is what a DPI setting names.
- Raw or accelerated
- Where the browser offers unadjustedMovement, the counts skip the system's pointer acceleration and are the mouse's own. Where it does not, the result says the counts went through the system's acceleration and may differ.
- Passes and spread
- Each pass is kept. From three, the median is the figure and the spread, max minus min over the median, shows how well they agree. Our line for disagreement is 10 percent.
- Against your setting
- Enter the DPI the mouse is set to and the result shows how far above or below it the measured figure is.
- A ruler on the screen
- No ruler? Enter the screen's diagonal and a ruler is drawn from it and the reported resolution, assuming square pixels and a native resolution, or match a bar to a bank card held to the screen.
If it fails
The usual failures, and what fixes each.
- The figure is far from the setting
- Check that the system's pointer acceleration (Enhance pointer precision on Windows) is off if the result says accelerated, and that the mouse's software has not set a different DPI stage.
- The passes disagree
- Move along a straight edge at an even speed, start and stop exactly on the marks, and keep the mouse flat. A pass with a lift in it is short.
- The pointer will not lock
- Click inside the page first; browsers lock the pointer only after a click. Leave any full-screen game or app.
Where a browser stops
What it cannot tell you.
- The distance itself. The page cannot see the desk: 1 mm off over 10 cm moves the figure by 1 percent.
- Raw counts in browsers that do not offer unadjustedMovement. There the figure includes the system's acceleration and scaling.
- Lift-off distance, tracking speed and polling rate. The mouse test measures the polling rate.
Privacy
Nothing leaves this page.
The camera and microphone are read on this page and stopped as soon as they have been measured. The clip you can play back lives in the browser's memory and is discarded when you leave. The location check discards the position. The internet test sends random bytes to this site and nothing else. The result is stored nowhere unless you ask for it by email, and then only the fact that an email was sent is kept.
Questions
Mouse DPI test, answered
- How do I check my mouse DPI online?
- Open the test, choose the distance you will move (a ruler, or a bank card's long edge), start a pass, move the mouse that distance in a straight line, and click. Do three passes; the median is the mouse's counts per inch.
- Is DPI the same as CPI?
- For a mouse, yes in practice. Counts per inch is the accurate name; DPI is the one on the box and in the software.
- Why does the test say accelerated movement?
- This browser did not give raw movement, so the counts passed through the system's pointer acceleration. The figure can differ from the mouse's own; run it in Chrome or Edge, which offer raw movement on the systems they support it on.
- Can I measure DPI without a ruler?
- Yes: use a bank card's long edge, 85.60 mm by the ISO/IEC 7810 standard. Or draw a ruler on the screen from its diagonal, check it with a card, and mark the distance on a strip of paper.
- Why does my mouse measure a different DPI from its setting?
- A sensor can deviate from its nominal setting, and the measured distance carries your own error. Measure several passes on a straight edge before reading a few percent as the sensor's.
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