How projection screen sizes are measured
Specify the visible image width, height and aspect ratio instead of relying on a diagonal number alone.
A practical note on diagonal, horizontal and visible image measurements, with the frame, casing, projector and seating kept in the same room brief.
A screen size is only useful when the measurement describes the image people will see. Record the visible width, visible height and aspect ratio, then add the frame, casing, border, mounting and room clearances as separate dimensions.
How screen size is described
| Measurement | What it tells you | Use it for |
|---|---|---|
| Diagonal | The corner-to-corner distance across the visible image area. | Comparing common wide-format screen sizes when the aspect ratio is already known. |
| Visible width | The horizontal image dimension from left to right. | Throw-distance calculations, wall planning and seating checks. |
| Visible height | The vertical image dimension from top to bottom. | Sightlines, screen drop, furniture clearance and image placement. |
| Outer envelope | The frame, casing, brackets, border and service space beyond the image. | Checking whether the installed screen fits the wall, recess or ceiling. |
The same diagonal can show a different image
A 100-inch diagonal does not describe one universal rectangle. A 16:9 screen is wider and shorter than a 1:1 screen with the same diagonal. The source article gives approximately 2214 × 1246 mm for a 100-inch 16:9 viewing area and 1778 × 1778 mm for a 100-inch 1:1 viewing area; confirm the selected manufacturer's visible dimensions before ordering.
Plan from the visible image
- Confirm the source aspect ratio before choosing the screen shape.
- Use visible width for throw-ratio and projector-placement planning.
- Use visible height for sightlines, furniture clearance and the top and bottom image edges.
- Keep the frame, casing, border, brackets and service access outside the visible image measurement.
- Check the nearest, furthest and widest seats rather than using only the centre seat.
Check image size in a room
Include aspect ratio, viewing distances, source content and a photo of the intended screen wall.
Check image size in a room