How tall should sign letters be? Viewing distance chart

For a wall sign, plan on about 1 inch of letter height for every 10 feet between the sign and the people you want to reach. A sign read from 100 ft needs letters of about 10 in. About 1 inch per 30 feet is the point where letters become readable at all, for a viewer with good eyes looking straight at the sign. Treat that as the floor, not the target.

The rest of this guide shows where those numbers come from, how speed and viewing angle change them, and how to check your own storefront.

The quick chart

Measure from the place where people first need to read the sign: across the street, the far end of the parking lot, or the point where a driver has to decide to turn in.

Viewing distance	Easy to read (1 in per 10 ft)	Bare minimum, straight on (1 in per 30 ft)
25 ft	2.5 in	1 in
50 ft	5 in	2 in
75 ft	8 in	2.5 in
100 ft	10 in	3.5 in
150 ft	15 in	5 in
200 ft	20 in	7 in
300 ft	30 in	10 in
500 ft	50 in	17 in

The 1-in-10-ft rule is the one sign makers have used for years, and US Sign Council (USSC) research on wall signs arrives at the same ratio. The 1-in-30-ft figure is the USSC’s average “threshold” legibility, and traffic engineers use the same 30 ft per inch for road signs. At threshold size, people can just make out the words if they stare. At three times that size (1 in per 10 ft), they read quickly and look away, which is what you want from a customer driving past.

Our letter height calculator does this math for you, and the letter height chart has more sizes.

What “letter height” means

Letter height is the height of a capital letter. In a word set in upper and lower case, it is the height of the first capital; the lowercase letters are shorter, and letters like g, p and y drop below the line. Keep that in mind when you compare quotes or drawings: ask whether a number means the capital height or the overall height of the whole line.

Wall signs beside a road: the angle matters

Most storefront letters are mounted flat on the building, parallel to the street. Drivers see them at an angle, and below about 30 degrees the letters are too foreshortened to read, no matter how big they are. So a wall sign has a limited reading window, and that window depends on how far the wall is from the traffic.

The USSC’s wall-sign model turns this into a simple formula:

Letter height (in) = (number of traffic lanes × 10 + distance from the curb to your wall, in ft) ÷ 5

Count the lanes on the road your customers drive, both directions. A few values from the USSC lookup table:

Wall set back from the curb	2 lanes	4 lanes
20 ft	8 in	12 in
40 ft	12 in	16 in
60 ft	16 in	20 in
100 ft	24 in	28 in
150 ft	34 in	38 in
200 ft	44 in	48 in

A shop in a strip center 100 ft back from a four-lane road needs letters of about 28 in to give drivers a fair chance. The same shop on a two-lane main street with the wall 20 ft from the curb can use letters of about 8 in.

Signs that face traffic: speed sets the distance

A blade sign, a sign on a wall that faces down the road, or a sign at the end of a street is read head-on. Here the question is how far away a driver must start reading. The USSC method multiplies speed (in feet per second) by the time a driver needs to notice the sign, read it and react. For a typical sign of about six words on a simple road, the USSC average is 8 seconds.

Speed	Feet traveled per second	Distance covered in 8 seconds	Letter height at 30 ft per inch
25 mph	about 37 ft	about 295 ft	about 10 in
35 mph	about 51 ft	about 410 ft	about 14 in
45 mph	about 66 ft	about 530 ft	about 18 in
55 mph	about 81 ft	about 650 ft	about 22 in

On busy in-town streets, with signals, on-street parking and many other signs competing for attention, the USSC reduces the 30 ft per inch figure to 25 or even 20. That makes letters 20 to 50 percent taller. Fewer words help too: a short name is read faster than a name, a slogan and a phone number.

Projecting signs read better than wall signs of the same size, which is why they work so well on walkable streets. See blade signs and projecting signs.

What else changes the answer

• All capitals. USSC research found that an all-caps word needs letters about 15 percent taller than the same word in upper and lower case to read from the same distance.
• Font. The research used plain sans-serif and serif typefaces. Thin scripts, light weights and very condensed fonts read from shorter distances. Choosing a font for channel letters covers what works.
• Contrast and light. The USSC tables give slightly different numbers for each combination of letter color, background and lighting, and lit letters on a dark background often score a little better. The differences are small next to distance and angle. Front-lit letters put the light on the letter itself; halo-lit letters read as solid shapes outlined by the glow on the wall, so they need good contrast with the wall color.
• Space around the copy. On a panel or lightbox, the USSC recommends that letters and logo cover no more than about 40 percent of the face, leaving the rest as open space. Crowded panels read worse than the letter height suggests.

Bigger is not always allowed

Two limits can stop you from simply going larger:

1. The city. Most sign codes cap total sign area, often tied to the length of your storefront. How cities measure sign area explains the methods.
2. The landlord. Shopping center sign criteria often set a maximum letter height or a maximum share of the sign band.

If the letter height you need is larger than the limits allow, shorten the copy before you shrink the letters. A name alone at the right height does more than a name, slogan and phone number squeezed in.

How to check your size

1. Measure the distance from the wall to where people will read it, or the setback from the curb and the number of lanes.
2. Run the numbers in the letter height calculator.
3. Type your name into sign preview to see how wide the sign gets at that height, and compare it with your wall. If you plan letters on a raceway, the raceway length follows from that width.
4. Cut one letter out of paper at full size, tape it up, and look at it from the street.
5. Send your text, logo and wall size through get a free drawing. The drawing shows the letters at their real size on your wall, with a lit preview and an exact price, and nothing is built until you approve it.

Height is the first design decision, not the only one; channel letter sign design tips covers spacing, contrast and copy length. For more storefront sizing ideas, browse our front-lit letters and storefront sign projects.