What Is Point Size in Typography?

A point is a unit of length, and point size is how that unit is used to name the size of a typeface. When a document says “11 pt Garamond” it does not say that any letter is 11 points tall. It says that the font was designed on a notional box 11 points high, and that every letter in it sits in that box.

A short history

Before the 18th century, typefounders cast type in named sizes with names such as Pica, Long Primer and Brevier, and different workshops could have slightly different sizes. In the 1730s, the French typefounder Pierre-Simon Fournier proposed a standard system based on a single unit, the point. François-Ambroise Didot refined it later in the century, and the Didot point, about 0.376 mm, remained the standard across much of continental Europe.

In Britain and the United States printers settled on a smaller point, roughly 0.351 mm, equal to 1/72.27 of an inch, and a pica of 12 points. The units were standardised in the US in the late 19th century. When desktop publishing arrived in the 1980s, PostScript simplified this to exactly 1/72 inch, and that digital point is the one used by most software today, including CSS. So there are three slightly different points in history: Didot, traditional Anglo-American and digital.

Point size is the em, not the letter

In metal type, the point size was the height of the metal body that carried the letter. The letter sat on that body with space above and below. Digital fonts keep the same idea with an em square, an imaginary box whose height equals the font size. The designer decides how tall the letters are inside it. A font with a large x-height and tall caps fills the box. A font with small lowercase letters leaves more empty space.

The result is that 12 pt in one typeface may look clearly larger than 12 pt in another. The standard way to compare fonts is to look at the x-height and cap height as a ratio of the em. A designer picking a body font for a wedding menu will often choose a point size 1 or 2 points larger for a font with a small x-height, in order to match the visual size of another font.

Points on screens

CSS defines 1 inch as 96 pixels and 1 point as 1/72 inch, so one point equals 1.333 pixels:

These are logical pixels. A phone may pack several physical pixels into each CSS pixel, so the real physical size on screen depends on the device.

Point size in lettering

Hand lettering is not set in points, since you draw each letter at the size you need. But points still help when you plan a piece that will be digitised or printed. If you plan an 8 by 10 inch print with a quote, deciding the main word is the size of a 72 pt headline (one inch em height) gives a frame of reference. When you move between a drawn piece and a typeset caption, point size ties the two together. The lettering image maker lets you set text sizes in pixels, and the same logic applies.

Typesetters also match leading to point size, with a common starting point of line spacing around 120% of the font size. Display type at large sizes usually needs tighter leading than body text, and display fonts are drawn for sizes above roughly 24 pt, with finer details and tighter spacing than text fonts.

Point size and fancy text

You cannot set the size of fancy text in a bio, caption or username, because the platform controls the font and size. What you can do is choose a style that suits the size you are given. Small letters from the small text generator shrink the visual size without changing the font size, and bold styles read better at the small sizes some apps use.

Common confusions

• Point is not pixel. On a standard CSS screen one point is 1.333 px.
• Point is not letter height. It is the em height; real letters are usually shorter.
• Point is not a unit of weight. Bold and light are font weights, not sizes.