This test needs a mouse
Measuring DPI needs a physical mouse and a desktop browser that supports pointer lock (Chrome, Edge, Firefox or Safari on a computer). Phones and tablets can't run it. You can still read how it works below, or use the sensitivity converter.
Measure
Longer distances give a more accurate reading.
Mark two points 10 cm apart on your mousepad, then press Start.
The cursor hides while measuring. Esc cancels at any time.
Measured — DPI
Runs
| Run | Distance | Counts | DPI | vs setting | Input |
|---|
How to get an accurate reading
- Put two marks on your desk or mousepad exactly the chosen distance apart. Use a real ruler or tape measure, not an on-screen ruler: display scaling makes on-screen sizes unreliable.
- Enter the DPI your mouse is set to, if you want to compare against it.
- Press Start measuring. Then line up the edge of the mouse with the first mark (you can lift and reposition freely at this point) and click or press Space to start counting.
- Slide the mouse in a straight line to the right until the same edge reaches the second mark. Keep it flat on the pad the whole way.
- Click or press Space to stop. Repeat three to five times and go by the average.
Longer distances give better accuracy: a 1 mm placement error is 1% over 10 cm but only 0.5% over 20 cm.
Why the reading can be off
The page can only count the movement the browser hands it, and that isn't always the raw sensor output.
- Pointer acceleration. Chrome and Edge on Windows and macOS can ask for raw, unaccelerated input, and this page does. Each run shows whether it got it. Firefox and Safari don't offer that option (nor does Linux), so the page can't confirm raw input there. Turn acceleration off before measuring: on Windows, untick Enhance pointer precision (Settings → Bluetooth & devices → Mouse → Additional mouse settings → Pointer Options) and leave the pointer speed on its default middle notch; on macOS, turn off Pointer acceleration (System Settings → Mouse → Advanced); on Linux, choose the flat acceleration profile.
- Display scaling and zoom. Browsers don't agree on the units they report movement in. Chrome and Edge use device pixels, while Firefox divides by your display scale and page zoom. Reset the page zoom (Ctrl/⌘ + 0) before measuring. If a reading is off by exactly your display scale (e.g. 1.5× or 2×), the page points that out.
- Technique. A slanted path, a mouse that tilts or lifts, or starting and stopping a little early or late all add error. Averaging several runs smooths most of it out.
Questions
How far off is normal?
Sensors are often a few percent away from the number they're set to, and this measurement carries a few percent of error of its own. Within ±5% is a match; a consistent 10% or more across several careful runs means the sensor really reads differently from its label.
Is DPI the same as CPI?
For mice, yes. The precise term is CPI (counts per inch: how many movement reports the sensor sends per inch of travel), but the industry calls it DPI. This page measures counts per inch.
My mouse is off. What now?
Nothing is broken; your aim just depends on the real number. Use the measured DPI in the sensitivity converter to get accurate eDPI and cm/360 figures, or nudge the DPI setting in your mouse's software. For a Redragon M913 or M908, that's the M913 configurator or the M908 configurator.
Is anything sent anywhere?
No. Everything runs in your browser and nothing is stored or uploaded.