Screen size and viewing distance

How it is worked out

The calculator uses the viewing angle: how much of your field of view the picture fills, measured across its width from your eyes. Width = 2 × distance × tan(angle ÷ 2), and the diagonal follows from the screen shape.

• 30° is the widely quoted SMPTE figure for the minimum that feels like a proper picture.
• 36 to 40° is the commonly cited THX range for a cinema-like view.

We could not check the primary SMPTE and THX documents, so the figures are labelled as widely quoted and commonly cited rather than as standards.

Can you see the pixels?

With 20/20 vision you resolve detail down to about one arcminute (a sixtieth of a degree). Beyond the distance where one pixel spans less than that, extra resolution is not visible. This is a rule of thumb: eyesight, content and processing all change it, and many people enjoy 4K further back for its HDR and colour, not its pixels.

Scope screens

For a 2.39:1 or 2.35:1 screen the angle is measured across its full width, so a scope screen gives a wider view than a 16:9 screen with the same diagonal. Seating for scope is usually chosen so that scope films fill about 40° or more.