If the aspect ratio of your pen tablet's active area does not match your monitor's aspect ratio. You will see distortion. The diagram below shows that if you trace out a circle on the pen tablet, you will have traced out an oval on the screen.
Don't worry! You can correct this. And it's important you do. Because not only does it produce a distorted drawing experience, the mismatch between what your hand is doing and what is happening on the screen can be incredibly frustrating.
This video goes into great detail about this topic. https://youtu.be/9oAvsJk5ESU
The issue with pen tablets is that the tablet and the display are separate devices. And each device has its own aspect ratio. The odds of the aspect rations matching by chance are very low. For example, as of 2024 most pen tablets do not have a 16x9 aspect ratio even though most displays do have a a6x9 aspect ratio.
If the aspect ratios match, then there is no distortion when you draw.
Here are some examples of what happens some Wacom pen tablets because of the mismatched aspect ratios when using a 16:9 monitor.
This mismatch of aspect ratios is SIMPLE to solve. All tablet drivers have a setting for this, although they call it by different names and the drive UI has a different way to enable it.
What this setting does is let you use only the region of the active area that matches to that of your monitor - so the aspect ratios will match.
Trade-offs
If you enable this setting you will not be able to take advantage of some of your tablet's active area, but BY FAR this is the better alternative than the distorted drawing.
Should everyone use this setting?
YES. I highly recommend it for for the vast majority of cases.
The setting is called Force Proportions.
Launch Wacom Tablet Properties
Under the Mapping tab, enable Force Proportions
The setting is called Screen Ratio.
Launch the HuionTablet App
Go to Working Area
On the bottom left there is a drop down.
Switch the dropdown to Screen Ratio.
The setting is called Screen Ratio.
Open the Gaomon driver app
Go to Workspace
Select Screen Ratio
The setting is called Proportion.
Open the XP-Pen driver app (called PenTablet)
Go to Work Area
Go to Pen Tablet
Select Proportion
The setting is called Screen Ratio
Open the Xencelabs driver app
Go to Device Settings
Look in Tablet to Screen Area Mapping
There's a drop down on the left side. It has three options: Full Tablet Area, Define Portion, and Screen Ratio
Select Screen Ratio in the bottom
The active area of a pen display and their display panel inside the pen display are equivalent. So they always match.