Original Tool · Drawn to Scale

Frame Fit.

Move the display, watch the wall change. Screen width, bar length, and the seating distance the room actually wants — drawn to scale, because a number on a spec sheet has never once settled an argument with a designer.

Screen width
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Screen height
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Bar length
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Seating · cinematic
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Seating · relaxed
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Why the bar matches the screenA bar cut to the display's exact width reads as architecture instead of equipment. That's the whole argument, and it's easier to make standing in front of a drawing than describing it over the phone.
The Math
Nothing here is a secret

A display's advertised size is its diagonal. For a 16:9 panel, the width is the diagonal times 0.8716 and the height is the diagonal times 0.4903 — straight from the aspect ratio. For 21:9 it's 0.9191 and 0.3939.

Seating distance comes from viewing angle. A 40-degree horizontal field — the cinematic end, what THX points at — puts you at about 1.37 times the screen width. A 30-degree field, the SMPTE recommendation and the more forgiving number for a family room, puts you at about 1.87 times the width.

Use it for
Settling the "will it look too big" conversation before the drawing goes out, and showing a designer why the bar length isn't negotiable.
Confirm before you order
Panel bezels vary and every model has its own overall dimensions. This is geometry, not a cut sheet — check the actual display and the actual bar before anything gets built.