A Rule of Thumb for Leading

If you have a lot of text to format, it can be wearying to adjust its leading by eye. Instead, try using this simple rule of thumb that involves the length of the line of type (also known as its “measure”):

When your type size (in points) is the same as your line length (in picas), set the leading to equal the type size β€” also known as “solid” leading. For example, 12 point type in a 12 pica column gets a leading value of 12.

When the line length (in picas) reaches twice the type size (in points), add one point of leading.

When the line length (in picas) reaches three times the type size (in points), add two points of leading.