Signs
ADA braille dot dimensions
Table 703.3.1 in full — five measurements with their tolerances, in the standard's own inches and millimetres.
These are the numbers that decide whether a sign can be read. They are tight: the spacing between lines is fixed within five thousandths of an inch.
| Measurement | Inches | Millimetres | Measured |
|---|---|---|---|
| Dot base diameter | 0.059 to 0.063 | 1.5 to 1.6 | — |
| Distance between two dots in the same cell | 0.090 to 0.100 | 2.3 to 2.5 | centre to centre |
| Distance between corresponding dots in the adjacent cell | 0.241 to 0.300 | 6.1 to 7.6 | centre to centre |
| Dot height | 0.025 to 0.037 | 0.6 to 0.9 | — |
| Distance between corresponding dots from one cell directly below | 0.395 to 0.400 | 10 to 10.2 | centre to centre |
Dot base diameter
0.059 to 0.063 in (1.5 to 1.6 mm) · 703.3.1
How wide each dot is where it meets the sign. The range is four thousandths of an inch.
Distance between two dots in the same cell
0.090 to 0.100 in (2.3 to 2.5 mm) · 703.3.1, centre to centre
The spacing inside one cell, between dot 1 and dot 2, or dot 1 and dot 4.
Distance between corresponding dots in the adjacent cell
0.241 to 0.300 in (6.1 to 7.6 mm) · 703.3.1, centre to centre
Dot 1 of one cell to dot 1 of the next. Note that it is corresponding dots, not the gap between the cells: the blank space between two cells is a smaller distance, and it is not the one the standard gives.
Dot height
0.025 to 0.037 in (0.6 to 0.9 mm) · 703.3.1
How far each dot stands off the surface. The smallest figure in the table.
Distance between corresponding dots from one cell directly below
0.395 to 0.400 in (10 to 10.2 mm) · 703.3.1, centre to centre
Line to line. The range is five thousandths of an inch on four tenths: the narrowest in the table for its size.
The rules that are not measurements
A sign can pass a calliper check on all five rows above and still fail the standard. These are the requirements that a measurement does not catch — and the raised text above the braille has a dimension table of its own.
| Requirement | Clause | Note |
|---|---|---|
| Braille shall be contracted (Grade 2) | 703.3 | Not a preference. Uncontracted braille on an American sign does not meet the standard, however carefully it is made. |
| Dots shall have a domed or rounded shape | 703.3.1 | The standard names the shape and gives no radius for it. Height and base diameter are in the table above. |
| Braille shall be positioned below the corresponding text, and below all of it where the text runs to more than one line | 703.3.2 | On elevator car controls the braille may sit directly below the raised characters or beside them. |
| Braille shall be separated 3/8 inch (9.5 mm) minimum from any other tactile characters and from raised borders and decorative elements | 703.3.2 | On elevator car controls the separation drops to 3/16 inch (4.8 mm). |
Checking a ready-made sign
Signs sold online are often described as ADA-compliant — this self-adhesive 9 × 6 inch unisex restroom sign, for one. That is the seller's claim, not something this site has measured. Hold its braille to the five rows of Table 703.3.1 above and to the rules after them: contracted braille, domed dots, set below the text and 3/8 inch clear of borders.
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Questions and answers
How tall are braille dots on an ADA sign?
0.025 to 0.037 in (0.6 to 0.9 mm), measured from the surface of the sign, under Table 703.3.1. The dots must be domed or rounded rather than flat-topped.
How far apart are braille cells on an ADA sign?
Corresponding dots in adjacent cells are 0.241 to 0.300 in (6.1 to 7.6 mm) apart, centre to centre — not the gap between the cells, which is a different and smaller measurement.
The rule about capital indicators has its own page — with the cost measured in cells.
Every dimension and rule on this page is from the 2010 ADA Standards for Accessible Design, published by the United States Department of Justice, checked against the standard's own text. These are the federal 2010 ADA Standards. A given project may also be under a state or local code with its own requirements, California's Title 24 among them. Check the standard itself before specifying a sign; every clause quoted here is linked to its source.