Well As more and more people pick up a gaming mouse its important to understand what all the settings mean for your mouse. But the main reason is to dispute the crazy amount of weird and sometimes incorrect info and to collate and aggregate all of the information that is out there about this important setting and function on a gaming mouse and how it can even help you in its application in video games.
CPI(Counts per inch) or more commonly referred to as DPI(Dots per Inch) (but doesn’t really represent how mouse functions but more on that later on) is a unit of measurement of the number of counts a computer mouse outputs per inch of linear movement.
How mice count
As the above definition states, a count is emitted by a mouse every CPI^-1 inches of linear movement. So the larger the CPI the less the distance per one count emitted. This is going to be the main premise that will help with how it can help as well as why it is disadvantageous at lower CPI’s. Optical mice sensors use this system of measuring movement of a mouse through a light sensor think a camera and just like a camera the more you expose the sensor the more the information you get but the more interference the sensor can pickup and send wrong information around movement.
Benefits for higher CPI
Well now that you can understand the basics of how mice measure their inputs but be aware that its a simple representation. Now Its clear from this that the higher the CPI goes the better precision you get with that smaller distance per one count so that the smallest movement you can do to measure one count is smaller another thing that come of this is the more inputs that are received so its smoother and you can provide more data to your computer which is especially helpful with mouse acceleration and reducing the stuttering caused by really low CPI. One other thing which has been recently pushed into the spotlight is the latency improvements with the higher CPI’s through BattleNonSense’s video and their testing method. This is the case for higher CPI’s because if your moving your mouse at the same speed and there is an instant change of your mouse direction, because of that lower distance per count a mouse with a higher CPI will detect and emit a count showing that it is moving an new direction faster than lower CPI’s. But this comes with a disclaimer because it is so highly dependent on how fast you can speed up your mouse in a new direction so while on avg assuming the same acceleration higher CPI will have lower latency to emit a count it may be more beneficial to improve that speed but still not to say that increasing it will be still better for latency.
Issues with higher CPI
Now your asking if higher CPI is so good should I just set my mouse’s CPI to the maximum? No of course not while it has all of the benefits that still get better the higher the CPI you run into the issue I talked about with sensor interference/noise which gets exponentially worse with the increase of the set CPI. But a good feature with most mice is smoothing out a period of time of measurements to remove the noise.
Now that we have these benefits and issues, we can theorize and create a method to find the best one to maximize the benefits till the smoothing effects the inputs. Because every mouse and sensor is different its quite hard to create a definite one for all of them but for most of the time if using a modern sensor you can look towards 3200 being a reasonable CPI for most mice because its not quite beneficial past it plus that you wont run into smoothing. But its always so good to test and find if there is an issue.
Why DPI is a bad term
Its the term that most people associate with the concept of CPI, but DPI doesn’t fit or represent what CPI is. DPI is a common term referring to the dot density of a printer where there is a grid of equally spaced dots with the same amount in a certain distance, often a line for a printer head. Which again doesn’t fit what happens in a mouse like if till a count but its rather a circle of movement all with a set distance of movement and when it moves through this circle it counts with the direction then there is a new circle centering on the point of crossing it. Now because it emits this count a more fitting term is CPI
Now a common fad that goes along with CPI’s is pixel skipping which while helps the idea of higher CPI’s helping for a better experience/performance but it misrepresents the issues of lower CPI and spreads bad information. Pixel skipping cant happen cause you cant rotate by a pixel angle that just doesn’t exist and its rather the effect of a low CPI and its large distance per count being more exaggerated with a higher sensitivity value(larger rotation per count).