Although VESA Size is very recognized, its standards are not law. Manufacturers tend to follow the guidelines, but not universally (even within a brand of TVs, some may be VESA compliant, some may not).
Some things to remember when measuring are:
- Measure from the centers of the holes
- Measure from the furthest 4 corners holes (if there are more than 4 holes)
- Be aware of any curve on the back of the TV that would affect mounting
Here’s a good “cheat-sheet” when measuring using inches—odds are good if your measurement is close to the ones listed here, it’s a good bet that’s going to be your VESA® standard measurement.