What TV size fits a 2-meter seat? The 30 to 40 degree range

Both figures are horizontal angles, the share of your view that the screen's width fills. The 40 degree figure is the THX target for a cinema style view. The 30 degree figure is widely quoted as SMPTE's, but it's an older reference and not a current rule, so use it as a geometry marker.

From 2 meters, 48-inch TVs fill 30 degrees and 66-inch TVs fill 40. Every size between those two is in the band, so the answer is a range and not one number. The angle depends on the screen's width and your distance, so a small change in where you sit moves the whole band.

Measure from the front of the screen to your eyes in the spot where you'll sit. From 2 meters, the 50-inch TV fills 30.9 degrees and the 65-inch TV fills 39.6. Pick the 50-inch TV for a view near the 30 degree reference, or the 65-inch TV for one near the 40 degree target. A 75-inch TV goes past the 40 degree target at 45 degrees, so it fills more of your view than THX asks for.

A 43-inch TV falls short of the 30 degree reference at 27 degrees, so it only makes sense here if you want a smaller picture. If you can shift the seat, moving it back narrows the view and moving it forward widens it.