Viewing distance calculator
How big does the screen need to be?
Set how far away people stand and what they need to read. We show the letter height you need and the smallest size that works.
| Size | At this distance | Lines that fit | Letters per line | Pixels blend from |
|---|
The quick answer
For one message of three short lines, in landscape. 30 feet per inch of letter height is our planning figure. 20 feet per inch is the safer choice for fast reading.
| Distance | Capital letters, 30 ft per in | Capital letters, 20 ft per in | Smallest size, 30 ft per in | Smallest size, 20 ft per in |
|---|---|---|---|---|
| 5 ft (1.5 m) | 0.17 in (4 mm) | 0.25 in (6 mm) | 10.1 in | 10.1 in |
| 10 ft (3.0 m) | 0.33 in (8 mm) | 0.50 in (13 mm) | 10.1 in | 10.1 in |
| 15 ft (4.6 m) | 0.50 in (13 mm) | 0.75 in (19 mm) | 10.1 in | 10.1 in |
| 20 ft (6.1 m) | 0.67 in (17 mm) | 1.00 in (25 mm) | 10.1 in | 11.6 in |
| 30 ft (9.1 m) | 1.00 in (25 mm) | 1.50 in (38 mm) | 11.6 in | 17.3 in |
| 40 ft (12.2 m) | 1.33 in (34 mm) | 2.00 in (51 mm) | 15.6 in | 21.5 in |
How we work it out
We plan on 1 inch of capital letter height for every 30 feet of distance. That is the road-sign planning figure reported by Federal Highway Administration research, which assumes 20/40 vision. For fast reading, 20 feet per inch is the safer choice. Road signs are not slides, and thin fonts, poor contrast and glare all make these numbers worse, so test a real slide if it matters.
Lines that fit assume a plain sans font with line spacing of 1.7 times the capital height. For pictures, our rule of thumb is that they read well from within about 10 times the screen height, and we call anything past 16 times the limit.
Pixels blend where one pixel takes up about one arcminute of your vision, the usual figure for normal eyesight. Screen sizes come from the drawing for each unit.
What to do with the answer
Letter height sets your slide design. If your words do not fit at that height, cut words before you buy a bigger screen.
Once the file is made, the content checker tests its shape and format, and the sign builder shows the unit next to a person.