fonttools-subset

generate optimized subsets of font files

TLDR

Subset a font to Basic Latin code points

$ fonttools subset [path/to/font.ttf] --unicodes=U+0000-007F

Write the subset with an explicit output path

$ fonttools subset [path/to/font.ttf] --unicodes=U+0000-007F --output-file=[path/to/subset.ttf]

Emit WOFF2 instead of TTF

$ fonttools subset [path/to/font.ttf] --unicodes=U+0000-007F --flavor=woff2

Keep only selected OpenType layout features

$ fonttools subset [path/to/font.ttf] --unicodes=U+0000-007F --layout-features=onum,kern

SYNOPSIS

fonttools subset [options] font-file

fonttools subset generates optimized subsets of font files by including only specified glyphs, Unicode ranges, or OpenType features. This is essential for web font optimization, reducing file sizes significantly by removing unused characters.The tool supports TrueType (.ttf), OpenType (.otf), WOFF, and WOFF2 formats. It can convert between formats during subsetting using the --flavor option.Common use cases include creating language-specific subsets, web-optimized fonts with only Latin characters, or icon fonts with specific glyphs.

PARAMETERS

--unicodes=RANGE

Unicode code points to include (e.g., U+0000-007F for Basic Latin)

--flavor=FORMAT

Output format: woff, woff2, or omit for original format

--layout-features=LIST

Comma-separated OpenType features to keep (e.g., kern,liga,onum)

--output-file=PATH

Specify output filename; defaults to input with .subset suffix

--text=STRING

Include only glyphs needed for the given text

--text-file=FILE

Include glyphs needed for text in the specified file

--no-hinting

Remove hinting instructions to reduce file size

--desubroutinize

Remove subroutines from CFF fonts

INSTALL

sudo dnf install fonttools

sudo apk add py3-fonttools

brew install fonttools

CAVEATS

WOFF2 output requires the brotli Python package. Some complex OpenType features may not subset correctly if dependent glyphs are excluded. Always test subsetted fonts thoroughly.