type measurement pica point measure depth of column

#TYPE MEASUREMENT PICA POINT MEASURE DEPTH OF COLUMN MANUAL#
#TYPE MEASUREMENT PICA POINT MEASURE DEPTH OF COLUMN FULL#

This gave its name to certain other characters whose widths were half an em wide, such as the nut fractions shown in Figure 4: But because em and en sound so much a like, an en was often called a nut in type shops of yore. If you consider the shape a lowercase m, this is a very clever name.

For them, indent values have to be explicit numeric values. No popular word-processing or page-layout program lets you do this, though. Traditionally, ems have also commonly been used to define paragraph indents, because this automatically reflects a proportional relationship between the size of the type and the indent that goes with it. Because the kerning adjustments used to position the characters of the fraction on the left were expressed in relative units - fractions of an em - they have the same net effect even when the fraction is tripled in size, on the right. Likewise, you can kern the numerator and denominator of a fraction, raise its point size by a factor of 10, and the positions of the elements of the faction will remain proportionally constant and correct.įigure 3. A character that’s 500 units (half an em) wide will be 6 points wide at 12 point, and 36 points wide at 72 point - always half an em.

The charm of relative measuring units in all these cases is that the same values apply no matter what the size of the type is.

#TYPE MEASUREMENT PICA POINT MEASURE DEPTH OF COLUMN MANUAL#

Most typesetting programs follow suit for manual kerning adjustments, as well as for tracking values. Kerning adjustments, which are also stored within fonts, are also expressed in thousandths of an em. This shows that in the Monotype system, the W was 17 units wide and the y, 9 units wide. Below are two characters superimposed on an 18-unit wide em square. Typefaces created for the Monotype composing machine were designed with character widths expressed in increments of one eighteenth of an em. (The TrueType and OpenType specifications allow for character widths to be expressed in units as small as 1/32,678 em, but that’s overkill by most measures.) By comparison, many venerable typefaces - such as Times New Roman - that were designed for hot-metal machine composition have character widths based on only 18 units to the em.įigure 2. The widths of characters in a font, for example, are commonly expressed in thousandths of an em. Measurements expressed as fractions of an em have scads of uses. The only typographic element that you can count on to be exactly one em wide is an em space.

#TYPE MEASUREMENT PICA POINT MEASURE DEPTH OF COLUMN FULL#

The red lines indicate the full width of an em for each column of characters. Not all M s are created equal, or equally wide. As shown below, an M can have number of widths, and it’s not normally a full em wide.įigure 1. The practical result of this is that everything measured in ems or fractions of an em always remains in constant proportion to your type even though the size of the type itself might change.Īlthough its name derives from the letter M, the width of an em is not related to the width of that letter. In 10-point type, an em equals 10 points. The size of an em depends on the size of the type you’re using. The fundamental relative measurement is the em. Relative measurements have no fixed value - the dimensions they express vary according to the situation.

For type in the English-speaking world, the basic absolute measurements are picas and points. Inches and feet are absolute measurements. One thing that makes type measurement unique is that it uses two parallel systems: absolute measurements and relative measurements.Ībsolute measurements always have the same, fixed values. But once you understand them, you can tap into their power to make your work better and easier. Even people who use type every day may not know these weird and obscure measuring terms for the job of setting type.

Type measurement pica point measure depth of column