Optical Size Variants
Typefaces which include such variants have subtle design adjustments meant to serve specific type sizes. These adjustments were always built into metal type. They were lost for a time, with digital type. If optical variants don’t exist in your chosen typeface, some detail may be lost if it’s set small. Similarly, they may sacrifice subtlety at larger sizes.
The adjustments typically made to the design to optimize it for different sizes are: for larger point sizes, the space between characters tightens, the space within characters closes up, the serifs become finer and the stroke contrast becomes greater. The x-height gradually diminishes. For smaller point sizes, opposite adjustments are made.
The point sizes below are merely a guideline. Use your judgement based on the specific type family in your design. Test your design by either printing it or viewing it on many different screens.
There are many names for optical variants. This is not an exhaustive list. It does include common ones.
Typefaces with Caption in their names are designed to be set at small sizes of approximately 6 to 8 points.
Typefaces with Text in their names are designed to be used for body copy, set at approximately 9 to 12 points.
Typefaces with Subhead in their names are designed to be set at larger than text sizes from 14 to 20 points.
Typefaces with Display or any other word meaning large in their names are designed to be set at 24 points and up.
Poster or Banner
Typefaces with Poster or Banner in their names are designed to be set over 72 points.