Handy-dandy copyfitting calculator

When you need to estimate copy length, you can calculate with extraordinary accuracy how much space a piece of text will take up in a given point size with these handy-dandy formulas. This is called ‘copyfitting’.

Using one of the formulas below, you can also calculate:

  • The number of words you need to fill a given space,
  • The column width needed to make a certain number of words make a particular length.
  • The font size and leading necessary if the number of words, the column width and the length are all fixed.

The formulas are flexible enough to handle leading, where the type has a font size set on a larger body, for example 10pt type on a 15pt body.

If the type has no extra leading and is set solid, say 10pt on a 10pt body, simply square the point size. In this example, point size x body size = 10×10 =102.

Length in cm =

number of words x point size x body size
______________________________________ 
column width in ems x 108

Number of words =
length in cm x column width in ems x 108
________________________________________
point size x body size

 

Column width in ems = words x point size x body size

length in cm x 108

 

The basic formula from which the others are derived is:

Words /cm =
column width in ems x 108
__________________________ 
point size x body size

 

When the number of words, the length and width are fixed, calculate the required point size with:

Point size =
column width in ems x length in cm x 108
_________________________________________
number of words