It's easy to talk about Braille, but when technical questions arise about how Braille measures, the answers become vague. So I decided to clarify once and for all the ideas about what the standard measurements of Braille are.

Braille is the tactile reading and writing system used by blind people. The tactile points that form the letters are contained within a rectangular space called a Braille cell. A complete cell is formed by three points vertically and two points horizontally and can contain up to six tactile points, with which up to 63 characters can be formed.

The arrangement and numbering of the points in a Braille cell is a topic you should already know before addressing the dimensions and distances between the points. If you don't know where point 1 is, or point 6, or point 4, I recommend reading the Tutorial Learn Braille in Ten Minutes.

Okay, up to this point it was easy, because you probably already knew this information. These are the basics that everyone knows, but now let's get to the technical information that interests us. Perhaps you're a Designer about to invent a new device to display or print Braille at zero cost, but you don't know how far one point is from another.

Braille always uses fixed-width characters, so each Braille character always occupies the same space, regardless of how many points are in the cell. Clear so far? While you can choose the font size when typing, Braille always remains the same size. This structure allows blind people to easily detect points and Braille cells by touch.

Braille points and cells have standard dimensions that are adhered to by major Braille producers and dedicated devices such as Braille displays or printers.

The dimensions and distances are:

• Diameter of a Braille dot: from 1.5 to 1.6 mm
• Height of a Braille dot: from 0.6 to 0.9 mm
• Distance between two dots in the same cell: from 2.3 to 2.5 mm. Let's clarify: point 1 is 2.5 mm away from point 4; or point 1 is 2.5 mm away from point 2; or point 4 is 5 mm away from point 6. This is the distance between adjacent dots in the same cell.
• Horizontal distance between the same dots of two adjacent cells: from 6.1 to 7.6 mm. Let's clarify: point 1 of one cell is 6.1 mm away from point 1 of the adjacent cell; or point 4 of one cell is 6.1 mm away from point 4 of the adjacent cell; or point 1 of one cell is 6.1+2.5 mm away from point 4 of the adjacent cell to the right; or point 1 is 6.1-2.5 mm away from point 4 of the adjacent cell to the left.
• Vertical distance between the same dots of two adjacent cells: from 10 to 10.2 mm. Let's clarify: point 1 of one cell is 10 mm away from point 1 of the cell below.

Clear? If it's not clear, it means you don't have the basics to understand the meaning. You should first know Braille and its structure. I hope these measurements have clarified once and for all how much space is needed to display or print Braille characters. Whether you're a Hardware manufacturer or a Software developer, you should always adhere to these measurements. Sometimes I notice Braille labels on medication boxes: they're almost imperceptible dots that don't adhere to Braille standards. But that's another topic I'll write an article about sooner or later.

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