@[email protected] has good advice. Generally, this is what is acceptable:
- if placed above a fireplace, it's too high
- if TV has to be angled down, it's too high
- if you are standing and tv is at eye level, it's too high
This tom's guide is a decent start: https://www.tomsguide.com/us/how-to-mount-tv,news-24719.html