A commonly asked question in Web forums is how many points there are in an inch. The intent is often to print a page with 1-inch or 2-inch letters. The answers given in the forums are always, or nearly always, that 1 inch is 72 points, and therefore 2 inches are 144 points. But is it true? Sometimes, sometimes not. The two concepts for which points often are used are stroke weights and font sizes. Stroke weight is the thickness of a line or the border of a rectangle, ellipse, polygon and other shapes drawn with vector graphics drawing software. Here, 72 points are exactly 1 inch, at least in some drawing programs.
But there is no general answer for font sizes. It depends on at least five factors:
- What typeface is used
- What character from that typeface is used
- Whether a lower-case letter or an upper-case letter is used
- Whether the distance is measured from the descender to the ascender, or just from the baseline to the ascender
- What software is used
So the only foolproof approach is something like printing a letter at two different sizes, for example 100 points and 200 points, and measure the letter heights. A ruler can be used, but for better accuracy, a vernier calliper is useful. Learn how to use a vernier calliper.
Divide the font size (points) by the number of inches found, and remember to write down the result together with the typeface name and what letter and software was used. The result is the number of points in an inch. The result for the 100-point letter should be the same, or almost the same, as that for the 200-point letter. If there is a considerable difference, it is a good idea to check the measurements and the calculations.