Screen Size Selection Guide
Screen Format
Standard Video - This is standard NTSC 1.33:1 or 4:3 (width:height) ratio. It is the ratio used in TV and standard movies, and is very popular with home theater situations. It is also used for presentations, as it is the format used by computer screens. It is measured across the diagonal, as is a TV.
HDTV - This is a 1.78:1 or 16:9 ratio, the same as found in High Definition TVs. It may be the most popular for home theater users, as it is a compromise between the width of widescreen and cinema screens with the height of a video format. HDTV Format is also measured across the diagonal.
Professional - Standard Letterbox aspect ratio 1.85:1 (width:height) ratio.
Cinemascope - 2.35:1 (width:height) ratio.
Selecting the Correct Screen Size
Screen size should be large enough for the audience seated the farthest from the screen to see image details. Those seated in the front should be able to view the full width of projected images comfortably. Screen size depends on the overall dimensions of the room, projector placement, audience size and seating arrangements. Typical eye level of a seated viewer is 42" - 48". When looking directly at the screen the viewer's eyes should fall at the lower third of the image area for comfort. Screen width should be approximately 1.5-2 times the distance to the optimum or primary viewing area. Height is a factor of width.
Screen Size Conversion Chart
Use the following chart to convert an existing NTSC video format screen size to either an HDTV or Letterbox format size.
Calculated using existing height
| NTSC (1.33) Viewing Area |
HDTV (1.78) Viewing Area |
Letterbox (1.85) Viewing Area |
| H x W |
H x W |
H x W |
| 43" x 57" |
43" x 77" |
43" x 80" |
| 50" x 67" |
50" x 89" |
50" x 92.5" |
| 57" x 77" |
57" x 102" |
57" x 105" |
| 60" x 80" |
60" x 107" |
60" x 111" |
| 69" x 92" |
69" x 123" |
69" x 128" |
| 87" x 116" |
87" x 155" |
87" x 161" |
| 105" x 140" |
105" x 187" |
105" x 194" |
Calculated using existing width
| NTSC (1.33) Viewing Area |
HDTV (1.78) Viewing Area |
Letterbox (1.85) Viewing Area |
| H x W |
H x W |
H x W |
| 43" x 57" |
32" x 57" |
31" x 57" |
| 50" x 67" |
38" x 67" |
36" x 67" |
| 57" x 77" |
43" x 77" |
42" x 77" |
| 60" x 80" |
45" x 80" |
43" x 80" |
| 69" x 92" |
52" x 92" |
50" x 92" |
| 87" x 116" |
65" x 116" |
63" x 116" |
| 105" x 140" |
79" x 140" |
76" x 140" |
How to Calculate a Custom Screen Size
Use the following formulas to calculate a custom size. The formulas will assist you in finding the viewing area only.
| NTSC (1.33) |
HDTV (1.78) |
| Video Format |
Video Format |
| Diagonal/1.667 = Height |
Diagonal x 0.49091 = Height |
| Height x 1.33 = Width |
Diagonal x 0.87247 = Width |
| Width/1.33 = Height |
Height x 2.0395 = Diagonal |
| Height x 1.667 = Diagonal |
Width x 1.14585 = Diagonal |
| |
Height x 1.78 = Width |
| |
Width x 0.561837 = Height |
| Leterbox (1.85) |
| Video Format |
| Diagonal x 0.4762 = Height |
| Diagonal x 0.88 = Width |
| Height x 2.10 = Diagonal |
| Width x 1.135 = Diagonal |
| Height x 1.85 = Width |
| Width x 0.5405 = Height |
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