CPI, DPI and Computer Mouse Selection Variables

Controller Master


When considering the sensitivity of a given mouse you’re using for your computer setup, whether for gaming or any other use, there are two metrics that might be used: CPI or DPI. The two terms might look similar at first glance, but there are important differences between them that you need to know about before making a purchase decision.

At Xidax, we’re here to help with numerous areas of computer and workstation setup, including our wide selection of tower options plus numerous accessories, including mice and their related factors. What are CPI and DPI metrics, how are they useful when selecting a mouse and monitor setup, and what are the other important factors to be aware of here? Let’s take a look.

Term Basics

  • CPI is an older term that refers only to how many times per inch the cursor moves on-screen when you move the mouse one inch across your desk surface, or “counts per inch.” It doesn’t take into account any other factors like acceleration or speed limits.
  • DPI actually stands for dots per inch, and is technically used to measure printer output — but this is not its primary use in reality. Rather, DPI takes into account not only movement on-screen for each inch moved by the user, but also other factors such as mouse acceleration, speed limits when using the entire surface of a mouse mat, and other pieces of hardware inside your computer.

A 120 DPI mouse is able to move more than twice as many pixels per inch as a 96 CPI mouse because it has hardware features that both increase sensitivity and ergo reduce movement speed.

A DPI of 800 doesn’t mean that the cursor will move at exactly 800 pixels per inch every time. It means that the cursor’s movement is limited by hardware and driver settings to no more than 800 pixels per inch, even if you move the mouse faster or slower than one inch in a single direction.

Examples and Uses

For example, a mouse may have the same CPI value of 800 regardless of whether or not it has software and hardware features that limit cursor movement to a maximum of 800 pixels per inch, or if it’s able to move the cursor 2,400 pixels per inch.

CPI can be used as an indicator of how sensitive a mouse is relative to other mice with identical CPI ratings, but it’s not an accurate way of comparing different mice that might have completely different hardware, software and driver settings.

CPI is an older term that’s fallen out of favour, which is why it’s no longer commonly used to describe mouse sensitivity by manufacturers. Instead, DPI (dots per inch) or “resolutions” are used from now on in most cases.

Sensitivity Comparisons

DPI and CPI measurements are also known as “sensitivity”. Which of these terms is used varies depending on which company or person you’re talking about. Some people still use CPI when talking about the sensitivity of their mice, while others use DPI or sensitivity instead.

DPI can be used as a way of comparing the sensitivity of one mouse to another, but it’s not relevant for comparing different sensors within a single mouse. You need to know the CPI rating instead in this case if you want an accurate comparison.

Now that we’ve been over the basics on both these metrics, here are some other factors that should be closely considered during mouse selection.

Size Factors

The physical size of the sensor on your mouse is also important. Smaller sensors are generally more accurate than larger ones. The smallest sensors are under 105 cubic mm in volume, and they’re generally found in some of the most expensive gaming mice that are sold today. Medium sized sensors range from 105 – 150 cm. Large sensor sizes overall are larger than 150 cm, and they’re generally used in more affordable models.

This is because larger sensors can be cheaper to make, and it’s easier to fit a smaller microcontroller and memory into the casing along with the sensor itself. Larger sensors can be used in more affordable models and still offer better performance than smaller models, though. They’re also often easier to pick up from a surface since they don’t have to be as light as smaller mice in order to reduce strain on users’ hands and wrists.

The exact size of a sensor isn’t always easy to find out in advance. Some manufacturers may not publish technical information about the sensors they use, and some third party specifications document sizes slightly differently. Some manufacturers don’t even specify what size mouse they’re using for their tests, which can make it more difficult to compare different products.

Sensor Shape

Sensor shape is also important. Most sensors are either circular or an oblong shape, but they can also be square, diamond-shaped and other shapes too.

The exact physical shape of a sensor can have a big effect on cursor control. Diamond-shaped sensors allow for diagonal motion that means mouse movement is more efficient than with other types of mouse sensors. This can help reduce strain on users’ wrists, hands and arms.

Directional Accuracy

Directional accuracy is another important factor to consider when buying a mouse. It determines how accurately the sensor can detect movement in a particular direction, instead of all directions at once. This also affects the DPI setting that’s used when measuring sensitivity. The higher the number for directional accuracy, the more finely controlled cursor movements can be.

There are some other less important factors to consider as well when buying a mouse, including polling rates and software features that limit or increase movement speeds on-the-fly. These aren’t always easy to define in advance, though, since they can depend on the hardware driver used by each mouse instead of the hardware itself.

In summary: DPI measurements can be used as a way to compare the sensitivity of a mouse against similar models. It’s not usually useful for comparing different sensors within a single mouse though, which is why CPI is more important in this case.

For more on this, or to learn about any of our gaming computers or the devices and accessories that work best for them, speak to the staff at Xidax today.