Mouse DPI Test: Measure Your Mouse's Actual DPI with a Ruler

Measure real pointer counts over a ruler distance, compare advertised DPI, and repeat calibration runs in your browser.

Mouse DPI & CPI Accuracy Tester compares a physical ruler measurement against the horizontal pointer movement your browser reports, using pointer lock to keep the cursor from hitting the edge of the screen mid-swipe. The number it produces is a DPI estimate derived from browser-reported counts after your operating system's own pointer processing, not a raw sensor readout, and the result panel says so directly.

The arithmetic behind the number

The measurement itself is simple: divide the counted horizontal movement, converted from millimeters, by the actual distance you moved the mouse, expressed in inches, since dots per inch is exactly what DPI means. Accepted inputs are a travel distance between ten and one thousand millimeters and an advertised DPI between fifty and fifty thousand, wide enough to cover both a short deliberate swipe and a full desk-length pull.

The result panel also shows percent error against whatever advertised DPI you entered, so you can see at a glance whether a mouse marketed at eight hundred DPI is actually reporting something close to that figure or noticeably off from it.

How to check your mouse DPI with a ruler

  1. Turn off Enhance pointer precision on Windows, or any pointer acceleration on your system, and leave the pointer speed at its default notch.
  2. Lay a ruler beside the mouse, then enter the travel distance in millimeters (10–1,000) and the DPI your mouse is currently set to (50–50,000).
  3. Put the cursor over the capture pad and press Start measurement; the pointer locks to the pad so it cannot hit the screen edge.
  4. Slide the mouse to the right by exactly that distance along the ruler, then press Stop or Escape.
  5. Note the measured DPI and the percentage difference, press Reset, and repeat three to five times before trusting the average.

What DPI (CPI) means for a mouse sensor

DPI, or more precisely CPI (counts per inch), is how many movement counts the sensor reports for each inch the mouse travels. At 800 DPI, one inch of travel produces 800 counts; at 1,600 DPI the same inch produces 1,600, so the cursor covers twice the distance for the same hand motion. Manufacturers use the two terms interchangeably.

A higher DPI is not automatically better. It only changes how far the cursor moves per inch of hand movement; accuracy depends on the sensor's tracking quality, and many players deliberately run modest DPI values paired with a matching in-game sensitivity.

What pointer lock buys you, and what it cannot fix

Requesting pointer lock on the capture pad keeps the operating system's cursor from moving at all during the test, so a long swipe does not run out of screen space or get clipped by a monitor edge; the reported horizontal count keeps accumulating regardless of where the now-hidden cursor visually sits. If pointer lock is not supported in your browser, the tool falls back to a plain warning telling you to keep the pointer inside the pad manually for the whole measurement instead.

What pointer lock cannot fix is that the reported movement is a value your operating system has already processed, through mouse acceleration, a pointer-speed curve, or scaling settings, before the browser ever sees it. That is exactly why the tool describes its own output as a browser-reported estimate rather than a sensor-level reading, and recommends disabling mouse acceleration for a result closer to the sensor's actual behavior.

Getting a measurement that actually means something

The suggested procedure is to lay a ruler next to the mouse, choose a precise distance, move only in that one direction for exactly that distance, then stop and repeat two or three more times; the tool tracks horizontal counts continuously while the test is running and lets you press escape or click stop to end it. Because hand movement is never perfectly straight or perfectly the intended length, repeating the measurement and comparing runs matters more than trusting any single pass.

Pressing Reset ends any capture that is still running and zeroes the count while keeping your distance and advertised DPI, so the next pass starts cleanly from Start measurement.

Mouse DPI vs. in-game sensitivity (eDPI)

Effective DPI, or eDPI, multiplies your mouse DPI by the in-game sensitivity setting: 800 DPI at a sensitivity of 0.5 gives 400 eDPI, the same feel as 400 DPI at a sensitivity of 1. Comparing eDPI is how players line up their aim feel across different mice and settings.

Windows pointer speed and acceleration are a separate operating-system layer applied after the sensor. They change how far the desktop cursor moves, and they can change what this test counts, but they never change the DPI the mouse itself is configured to report.

What this measurement cannot claim to be

Questions people ask about Mouse DPI & CPI Accuracy Tester

Why do I get a different DPI number every time I run the test?
Mostly because your hand does not move exactly the same distance in exactly the same line every time, and any operating-system mouse acceleration compounds that variance. Run the measurement several times at the same distance and look at the spread of results rather than trusting a single reading.
Does this measure my mouse sensor's actual, real DPI?
Not directly — it measures the horizontal pointer movement your browser reports after your operating system has already applied acceleration and pointer-speed processing to the raw sensor counts. Disabling mouse acceleration gets the reading closer to the sensor's real behavior, but it remains a derived estimate rather than a firmware-level readout.
What if my browser does not support pointer lock?
The tool detects that and shows a warning instead of silently failing; you will need to keep the cursor inside the capture pad manually for the entire measurement, since the pointer will move normally instead of staying locked in one place throughout the test.
What travel distance should I use for the most accurate test?
Anywhere from ten to one thousand millimeters is accepted, but a longer, carefully measured distance generally reduces the relative impact of small measurement errors compared to a very short swipe. Whatever distance you pick, keep it consistent across repeated runs so the comparisons actually mean something.
Can I check my mouse DPI without installing software?
Yes. The whole measurement runs on this web page: you need a ruler, a browser that supports pointer lock, and a few careful swipes. Without pointer lock the page warns you, and you must keep the cursor inside the capture pad for the full swipe yourself.
Does Windows pointer speed or Enhance Pointer Precision change my DPI?
They do not change the DPI the sensor reports, but they do change the movement the browser receives, and that is what this test counts. Turn Enhance Pointer Precision off and keep pointer speed on the default middle notch, sixth of eleven, which applies no scaling.
Does screen resolution affect the DPI result?
No screen calibration is needed: the tool adds up the movement counts reported during your swipe and divides by the ruler distance, so resolution is not part of the formula. If results look off by a round factor like 1.25 or 1.5, retest with display scaling at 100%, because some browsers scale reported movement.
Why is my result 790 instead of 800?
Small gaps are normal. Stopping just one millimeter short on a 100 mm swipe turns a true 800 into about 792, and real sensors often differ slightly from the advertised figure. The tool rounds to the nearest whole DPI rather than snapping to 50 or 100 steps, so average several runs.
What DPI should I use for gaming?
There is no single right value. Many players pick a DPI their mouse handles cleanly, commonly somewhere between 400 and 1,600, then fine-tune aim with in-game sensitivity. Compare setups by eDPI, and once your measured DPI matches the advertised one, your sensitivity conversions will be reliable.

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Content reviewed 2026-09-27.