Why's type measured in points?

What’s the point of points?

When we design, generally speaking, we set our typefaces in points (pt). 12pt, that’s a classic. 10pt, you’re pushing your client a bit there. 64pt, now we’re talking. But it’s a slightly confusing system since it’s not a standardised measurement – 12pt in Arial won’t be the same x-height as PP Palma (go check it out), for example. Could we use millimetres? Maybe. But we don’t. Instead, we’re using the remnants of a much older measurement system. The point is not a measurement invented for computers, but comes from the world of metal type, where printers needed a consistent way to describe the size of letters, spacing and pieces of type.

As we know – especially if you’ve been a long-time subscriber to our history-and-sports-leaning newsletter for a while – before digital fonts, type was physical. A typeface was cast as individual pieces of metal, with each little letter occupying a rectangular block. The height of that block was called the body size. A 12pt piece of metal, for example, was roughly 12 points tall, regardless of how large the actual letterform appeared within it. This distinction is still important today: a 12pt font does not necessarily have 12pt-tall capitals. The point describes the nominal type size, not the visible height of the glyphs. Hence why PP Palma and Arial appear differently sized, despite being set in the same point size.

The point came about alongside another unit: the pica. Another historical piece of typographic architecture… One pica contains 12 points, and six picas make up one inch. So it does come from measurement, albeit not metric (you’ve got that going for you, Americans). In the traditional Anglo-American system, that makes one point equal to 1/72 of an inch, or approximately 0.3528 mm – easy peasy. A pica is therefore 4.233 mm. These relationships made the system particularly useful for setting type because sizes and spaces could be combined into predictable increments.

Picas were commonly used for larger measurements in typography and printing, while points were used for smaller ones. A designer might specify a page as 30 picas wide, with 12pt type and 14pt of leading. This creates a system in which the scale of the page, the size of the type and the spaces between lines all relate to one another. It’s the basis of good hierarchy too. As an aside, this is something that this particular writer would say is being lost in good typographic practice due to the proliferation of non-type-favouring design softwares like Figma. The relationships between point size, leading and scale are becoming more arbitrary, and the nicely designed type suffers because of it.

The point system also solved a practical problem, that being the working relationship between printers and type foundries. Without standardised measurements, a 12pt type size from one manufacturer could be completely different from another. Standardisation made it possible to specify, order and arrange type with some degree of consistency.

All that said, there is – however – a small complication: there has never been one universal definition of the point. The traditional American point is exactly 1/72.27 of an inch, while the modern desktop publishing point adopted by software, like InDesign, is generally 1/72 of an inch. The difference is tiny, but arguably makes the whole system somewhat redundant. Just a friendly reminder that type is built on conventions, more than absolute measurements.

Despite points and picas seeming like unnecessary relics – especially when we can work in millimetres or pixels most of the time – they are still useful. They embody a distinctive period of typographic history, particularly the burgeoning power of print and physical type. More importantly, they provide a scale designed specifically around type, a reproducible, modular system. A piece of typographic infrastructure!