Viewing Distance Calculator
Are you sitting close enough to see 4K?
SMPTE Recommended Viewing Distance (30° FOV)
Feet
Max Distance to perceive 4K benefit
Feet
If you sit further away than this, human eyes cannot distinguish 4K from 1080p on this screen size.
The Limit of Human Vision
The human eye has a finite resolving power (roughly 1 arc-minute or 1/60th of a degree). If you sit 15 feet away from a 55-inch 4K TV, the pixels are so physically small at that distance that your eye blurs them together. At that distance, a 1080p TV looks identical to a 4K TV.
To get the benefit of a 4K purchase, you must either buy a massive screen or move your couch closer.