I only recently realized that there are more measurement systems for the design industry than there are types of design software. Picas, Points, Pixels, Agate, Inches, Metrics and of course the most random of all in my opinion, Ciceros. I have attempted to make a complete picture of all measurements used in design and when/if to use them.
I have paraphrased www.Wikipedia.org and would like to thank them for creating an incredible outlet for sharing information. Please visit their website for more detailed definitions of each of the measurements:
Pixel as defined on Wikipedia.org In digital imaging, a pixel is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled.
Pixels are primarily used for website design since websites are entirely dependent on the display device or in other words the computer screen that the end user uses to view the website. Pixels are very difficult to use for print design and I do not recommend it.
Picas as defined on Wikipedia.org A pica is a typographic unit of measure corresponding to 1/72 of its respective foot, and therefore to 1/6 of an inch. The pica contains 12 point units of measure. A measurement in picas is usually represented by placing a lower case p after the number, such as "10p" meaning "10 picas." Points are represented by placing the number of points after the p, such as 0p5 for
"5 points," 6p2 for "6 picas and 2 points". An 8.5"x11" sheet of paper is measured as 51p x 66p.
I have never used Picas in the past and thought at one time that they were the standard for print design. However I couldn't find anything definitive that said I should be using them. I have seen designs created using Picas and Points, but have yet to attempt a design using that unit of measure. I really haven't found a use for it since most print design depends on the sheet size you are designing for and in the U.S. sheets are measured in inches. In the rest of the world sheets are measured in metrics. Since the sheets are not measured in Picas then why should I use them for design? If you have the answer as to why I should be using Picas, please send me a comment and let me know!
Points as defined on Wikipedia.org In typography, a point is the smallest unit of measure, being a subdivision of the larger pica. It is commonly abbreviated as pt. The point has long been the usual unit for measuring font size and is used in both print and web design. The general math comparison to inches and milimeters is below.
1 point = 1⁄72 inches = 25.4⁄72 mm = 0.3527 mm.
Points have become the standard for type in both web and print design. It is almost impossible to avoid creating any kind of computer document without choosing what point size the font should be.
Below are two units of measure that I was completely ignorant of until I noticed in InDesign that they were options for measure:
Ciceros as defined on Wikipedia.com A cicero is 1⁄6 of the historical French inch (I can't believe there is something called a French inch), and is divided into 12 points. The measure-term cicero is thus used similarly to an English pica, although the French inch was slightly larger than the English inch; there are about 1.063 picas to a cicero. Cicero = 4.5 mm. Pica = 4.23333333 mm. So really, does anyone use this system of measurement? Please write to me if you do!
Agate as defined on Wikipedia.com An agate is a unit
of typographical measure. It is 5.5 typographical points, or about 1/14
of an inch. It can refer to either the height of a line of type or a font that is 5.5 points. An agate font was commonly used to display statistical data or legal notices in newspapers. It is considered the smallest point size that can be printed on newsprint and remain legible. My co-worker mentioned that he used to use agates when he worked for a newspaper printing company, but he hasn't seen anything in years that required the use of the agate.
Metrics vs. Inches. I would love to switch to the metric system, however it is not possible in the United States printing industry as it is today. Paper is always measured in inches in the U.S. Inches can be extremely frustrating, for example try to properly tri-fold an 8.5"x11" sheet of paper. The decimal points given after completing the math is unbelievable since one panel has to be .1" smaller than the other two panels. Metrics seem so clean, so easily divisible and it has my vote.
I realize I wrote a lot of words for one simple conclusion about Units of Measure: What to use When. Design in the measurement system that your printer would prefer. I use the inch system since all of our equipment and paper supplies rely upon the inch system, if I were designing for an international printer, I would use the metric system.
