Digitizer resolution and density
Background on tablet digitizers
The digitizer is the mechanism inside all EMR drawing tablets that:
Sends power to the pen through an electromagnetic signal
Senses a returning electromagnetic signal from the pen
From the returning electromagnetic signal, the digitizer can get information about:
The pen position
The amount of pen tilt
How much pressure is being applied
The status of the buttons
Digitizers are capable of distinguishing the position of the pen with very high precision.
Terminology
When dealing with this topic, it is helpful to clarify two terms. Not everyone uses these terms as defined below. However, we will use these definitions throughout this document.
For any rectangle that is composed of or can be decomposed into smaller elements:
Resolution refers to the dimensions — the width and height of an area in a given unit. For example, 1920 pixels by 1080 pixels.
Density refers to how many elements are packed into a given length. For example, pixels per inch or lines per inch.
Digitizer density
You will often see a tablet digitizer's density given in LPI (lines per inch).
A typical modern value is 5080 LPI. For every inch on the digitizer, the tablet can detect 5080 distinct positions.
This density is easier to work with in centimeters or millimeters.
So, 5080 LPI = 200 LPmm.
It is very common to see density labeled as resolution.
Densities <100 LPmm were for very tablets.
Modern tablets have been at >=100 LPmm for a long time now.
Almost all contemporary tablets have 200 LPmm
Digitizer resolution
Digitizer resolution is almost never listed. However, you can calculate it from the active area's dimensions and density.
For example, the Wacom Intuos Pro 2025 M has the following specifications.
Dimensions
10.4 × 5.8 in
263 × 148 mm
LPI (aka Density)
5080 LPI
200 LPmm
The digitizer resolution is 52,600 × 29,600 addressable elements.
In practice, nobody discusses digitizer resolution in these units.
Relation to a display
All drawing tablets use some form of display. This can be a separate monitor or a display embedded in the drawing tablet.
Displays have their own native resolution and size, so they have a pixel density.
Here are some common examples:
27" 4K display
166
27" 8K display
326
16" 4K display
283
Samsung Galaxy S21 series
~500
6th and 7th generation iPad minis
326
Overall, drawing tablet digitizers are 10 times denser than the best available displays. Even very old digitizers have a density of 2540 LPI (100 LPmm).
Implications for buying a drawing tablet
You don't need to worry about this LPI specification when selecting a drawing tablet. You will not be able to tell the difference between 2540 LPI and 5080 LPI.
My advice: Do not consider LPI or LPmm when making a purchase decision.
Position data sent to the computer
Even if a digitizer has an incredibly high resolution, you may wonder what data it sends to the computer.
The answer is simple: the digitizer sends its coordinates using the highest resolution available.
Somewhat related but very important: Force proportions
Resolution and density are not important when discussing tablets. However, another topic involves both the tablet's digitizer and a display. You should pay close attention to it. It affects your drawing quality and feel.
Enable Force Proportions in the tablet driver. See Matching aspect ratios with Force Proportions.
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