The short answer
- Allow about 1 inch of capital letter height for every 30 feet of distance. That is 8.5 mm of letter at 10 feet.
- Seven of our eight sizes have the same 1920 x 1080 pixels, so a larger screen makes the same slide physically bigger. It does not give you more detail.
- A 60 pixel line of text reads from about 13 feet on the 15.6 inch and about 20 feet on the 23.8 inch.
- If your longest distance is over about 30 feet, these screens only suit a few very large words. Buy a larger screen.
The distance rule
The best published numbers on legibility come from road signs. Federal Highway Administration research reports the federal sign manual's planning figure of 30 feet of reading distance per inch of letter height, which assumes 20/40 vision. We use 30 throughout this site. One of its studies of electronic message signs suggests about 20 feet per inch for 20/40 vision, so 20 is the safer choice for fast reading, or if your readers are older.
| Distance | Capital height | At 30 ft per in | At 20 ft per in, safer |
|---|---|---|---|
| 5 ft | 0.17 in | 4.2 mm | 6.3 mm |
| 10 ft | 0.33 in | 8.5 mm | 12.7 mm |
| 15 ft | 0.50 in | 12.7 mm | 19.0 mm |
| 20 ft | 0.67 in | 16.9 mm | 25.4 mm |
| 30 ft | 1.00 in | 25.4 mm | 38.1 mm |
Treat these as starting points. People reading a sign in passing need larger text than people standing still in a queue. If you are not sure, print a line at the size you plan on and tape it to the wall.
What that means in pixels
Your design software works in pixels, so here is the same rule per screen. Each screen has a fixed pixel size, calculated as the active area divided by the number of pixels.
| Size | 5 ft | 10 ft | 15 ft | 20 ft | 30 ft |
|---|---|---|---|---|---|
| 10.1 in | 25 px | 50 px | 75 px | 100 px | 150 px |
| 11.6 in | 32 px | 63 px | 95 px | 126 px | 189 px |
| 13.3 in | 28 px | 55 px | 83 px | 110 px | 166 px |
| 15.6 in | 24 px | 47 px | 71 px | 94 px | 142 px |
| 17.3 in | 21 px | 42 px | 63 px | 85 px | 127 px |
| 18.5 in | 20 px | 40 px | 59 px | 79 px | 119 px |
| 21.5 in | 17 px | 34 px | 51 px | 68 px | 102 px |
| 23.8 in | 15 px | 31 px | 46 px | 61 px | 92 px |
Capital height in pixels, at 30 feet per inch. Applies in landscape and in portrait, since the pixels are the same.
Note how the 10.1 inch behaves. It has fewer pixels, 1280 x 800, and they are close to the physical size of those on the 15.6 inch. So its numbers land close to the 15.6, even though the screen is much smaller.
The sizes compared
| Size | Outside, mm | Outside, in | Active area, mm | mm per pixel, calculated | 60 px text reads to (ft), calculated |
|---|---|---|---|---|---|
| 10.1 in | 293.6 x 193.6 | 11.6 x 7.6 | 216.6 x 135.4 | 0.169 | 12 |
| 11.6 in | 323.7 x 218.5 | 12.7 x 8.6 | 257 x 145 | 0.134 | 10 |
| 13.3 in | 373.6 x 245.2 | 14.7 x 9.7 | 294 x 165.6 | 0.153 | 11 |
| 15.6 in | 420 x 269 | 16.5 x 10.6 | 344.16 x 193.59 | 0.179 | 13 |
| 17.3 in | 458 x 291 | 18 x 11.5 | 383.28 x 216.21 | 0.200 | 14 |
| 18.5 in | 486.5 x 307.4 | 19.2 x 12.1 | 410.8 x 231.4 | 0.214 | 15 |
| 21.5 in | 557 x 345 | 21.9 x 13.6 | 476.64 x 268.11 | 0.248 | 18 |
| 23.8 in | 606 x 376 | 23.9 x 14.8 | 528 x 297.5 | 0.275 | 20 |
Outside sizes from each spec sheet. Active area from the screen outline on each drawing. The last two columns are calculated from those.
For a feel of the scale, use the builder. It draws your sign at true size next to a person. The viewing distance tool does this page's sums for your own room.
A starting point by place
| Size | Typical place | Usual distance |
|---|---|---|
| 10.1, 11.6 | A shelf, a register, a meeting room door | About 5 ft |
| 13.3, 15.6 | A check-in desk, an elevator car, a short notice | 5 to 10 ft |
| 17.3, 18.5 | A corridor, a retail fixture, a line station | 10 to 15 ft |
| 21.5, 23.8 | A menu over a counter, a waiting room, a lobby | 10 to 20 ft |
Our view from how the screens are used. Your room decides.
More on each place: elevators, menu boards, lobbies, retail, factory floors and waiting rooms.
Depth and brightness can overrule the distance rule. The 18.5 inch is our brightest panel, and the 11.6 inch is our shallowest at 51.5 mm. The display guide covers those.
Where this is the wrong choice
- Reading distance over about 30 feet. On the 23.8 inch, normal text at that distance needs 92 pixels of capital height, so only about 6 lines fit. A larger screen will serve you better.
- A room with one screen for everyone. A single 23.8 inch at the front of a large hall will not carry. Several small screens can work, but only if you can power each one.
- Fine print. If a slide has to carry legal text or a dense table, no small screen handles that at a distance. Use paper or a QR code for the detail.
Questions
How do I choose a digital signage screen size?
Start from the longest distance a reader will stand. Allow one inch of capital letter height per 30 feet, then check how many lines of that height fit on each screen.
What is the best screen size for a small business sign?
A menu over a counter or a notice in a waiting room is read from 10 to 20 feet, which suits 21.5 or 23.8 inches. A desk or a register, read at about 5 feet, suits 10.1 to 15.6 inches.
How big should text be on a digital sign?
At least 8.5 mm of capital height at 10 feet and 17 mm at 20 feet. That is about 47 pixels on a 15.6 inch screen at 10 feet, and about 61 pixels on a 23.8 inch screen at 20 feet.
Does a higher resolution help on a small screen?
Only when the reader is close. Seven of the eight sizes here are 1920 x 1080. Text height is what decides legibility at normal distance.
Planning information, not legal or engineering advice. Rules differ by place: check codes and permits with your local authority and your licensed trades.