“Spacing” (SPAC
in CSS) is an axis found in some variable fonts that can be used to adjust the spacing among characters overall, as a percentage from the default spacing.
The Google Fonts CSS v2 API defines the axis as:
Default: | Min: | Max: | Step: |
---|---|---|---|
0 | -100 | 100 | 0.1 |
Manipulating this axis has the same effect as adjusting the tracking value (called letter-spacing in CSS); therefore it can alter the personality of the type in the same way as tracking can, and — as with the Shantell Sans font — that effect can be further exaggerated by manipulating axes like Bounce (BNCE
) and Spacing in tandem.
The number system of the axis is a relative percentage, where the default spacing is zero,the minimum spacing is -100%, and the maximum (widest) spacing is 100%, with values up to one decimal place (e.g. 97.5%).
Manipulating the Spacing axis can be better than adjusting tracking settings because it’s often much more fine-grained (compared to the CSS letter-spacing
property) and offers the type designer an opportunity to structure changes to spacing in a sophisticated way, specific to each typeface. Fonts with a Spacing axis can be used to better finesse animations, and apply tracking adjustments in software which do not provide built-in support for tracking yet do support variable fonts.
For font developers, Google Fonts has commissioned a reference implementation of the Spacing axis, and tools to implement it, at github.com/googlefonts/roboto-flex-spacing-axis-demo.