A vexing problem made worse that google has been spammed to the point that all articles say the same thing [1] :-). I move monitor between three positions on a regular basis: Sit, Stand and Walking. When I move it, my eyes tell my brain that the monitor isn’t level.
Short of keeping a 3ft carpenters level on my desk. (Ugly). What pragmatic approaches have you found work?
[1] A google searches on the subject find results about ergonomics - cool and not what I need.
Search for “small self-leveling platform” or “small automatic self-leveling platform” or “small motorized self-leveling platform” for possibly better results. 
Use the level in the Measure app on your iPhone.
Some large TVs come with a very small spirit level to help the fitter ensure that they’re level.
See if someone has one you can temporarily fit to the monitor for a while.
I level with my phone as well (only if it’s bothering me, though.)
@tomalmy cool - I didn’t know this utility existed
@timstringer you upleveled Tom, well played.
@cornchip Yes and it always bothers me. I always wonder is it level?
The trouble with using an iPhone as a level is that we’re running out of flat sides on them. There are buttons down both sides and a camera bump on the back.
You can long press to toggle setting 0 degrees to the current angle. But the buttons do mean there are fewer situations where you can let go of the phone.
This just gives me another reason to keep my iPhone 13 past it’s planned retirement date. (2 yrs from now).
I was going to keep as a webcam. Webcam + level. Bonus
