Work out line height and spacing instantly with clear inputs, formula shown and shareable results.
Line height is the font size times the ratio, and the comfortable column width is the character target times roughly half the font size, since an average character is about half an em wide. Long lines need more leading, which is why the classic 45 to 75 character measure and a 1.5 ratio are paired rather than chosen independently.
Line height
line height = font size x ratio
Column width
width = characters per line x font size x 0.5
line height = font size x ratio. Line height is the font size times the ratio, and the comfortable column width is the character target times roughly half the font size, since an average character is about half an em wide.
Long lines need more leading, which is why the classic 45 to 75 character measure and a 1.5 ratio are paired rather than chosen independently.
Enter font size, line height ratio, target characters per line. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.