Measure (or Column Length or Width): The length of a typeset line from left to right given in picas. The pica measurement of a line of type, is written “x 24” (24 picas wide) and spoken “by 24 picas.” Or “set on a 24 - pica measure.”:

Some guidelines:

• Use 40 to 70 characters per line (approx. 812 words).
• Increase leading if line length is longer.
• Sans serif type works better in narrower column (not more than 60 characters per line).
• Line length = 30 times the size of type (20—40 picas); example: l0 pt type x 30 = 300 pts or 25 picas (300/12).
• Typical lowercase alphabet length for l0 pt text = 128 pts; therefore, a 25 pica measure = 65 characters per line.

Given the guidelines above, keep in mind that other factors, such as the design of the face and the nature of the material, must also be taken into consideration.

Leading (or Line Spacing or Interline Spacing or Baseline to Baseline Spacing): The amount of vertical space between lines of type. Leading measurements are expressed as two numbers: the typeface point size followed by the baseline to baseline measurement:

• 10/12 (read “10 on 12,” or “10 over 12,” as in a fraction) designates 10 - point type with 2 extra points (12) added for leading.
• 10/10 is called “setsolid” and has no extra space between lines (10 point type and 10 point leading). An indicator of good type design: When “set solid,” that is, no extra leading added, type is still readable, and ascenders and descenders don’t touch each other.
• For body text leading, a good rule of thumb is to add approximately 20% to the point size.
• 10 - point body text plus 20% = 12 points of leading, or 10/12.
• 9 - point type plus 20% rounded up = 11 points of leading, or 9/11.

Rough guidelines for leading

• 9, 10, 11- point type needs 1 to 3 extra points leading
• 12 - point needs 2 to 4 extra points
• 14 - point needs 3 to 6 extra points
• 16 - point needs 4 to 6 extra points
• 18 - point needs 5 to 6 extra points

Generally, consider adding more leading when using sans serif type for body text because uniformity of line weight makes it harder for the reader to track.

In the guidelines above, the higher leading value would more likely be applied to sans serif body text.

Headings require less leading (even negative leading), because too much space makes the text look choppy