I like to sit in front of a 24' screen, about 50 cm wide and 29 cm high, from a pretty standard distance of roughly 70 cm. Clicking tan^-1 on my trusty calculator and rounding up tells me it's covering an horizontal angle of 40 degrees, a vertical angle of 24 degrees.

Like the plurality of Steam users, I have a modest display resolution of 1920x1080 pixels [1]. In other words, I am comfortable with 1920/40 = 48 pixels per horizontal degree and 1080/24 = 45 pixels per vertical degree.

Humans have a binocular field of view of about 200 horizontal degrees and 135 vertical degrees [2]. To satisfy my modest resolution requirements, I would therefore need 200x48 = 9600 horizontal pixels and 135x45 = 6075 vertical pixels.

Current headsets do not actually cover the full human field of view, so let's consider the current favorite, the HTC Vive. It does about 100 horizontal degrees and 110 vertical degrees, according to [2]. That would work out to 100x48 = 4800 horizontal pixels and 110*45 = 4950 vertical pixels, i.e. more than 8k UHD.

Ways around that (apart from the obvious) are foveated rendering and alternative display technologies (light field displays).

[1] http://store.steampowered.com/hwsurvey

[2] https://www.vrheads.com/field-view-faceoff-rift-vs-vive-vs-g...