Formats & Containers

Understanding font file formats and containers helps you work with fonts across different platforms and use cases.

Font Formats

Font Format refers to the internal structure of the font file. Different formats have different capabilities.

Comparison Table

Format	Extension	Outlines	Features	Variable	Notes
TrueType	.ttf	Quadratic Bézier	Full	Yes	Most common
OpenType (TT)	.otf, .ttf	Quadratic	Full	Yes	TrueType outlines
OpenType (CFF)	.otf	Cubic Bézier	Full	Yes (CFF2)	PostScript outlines
PostScript Type 1	.pfb, .pfa	Cubic	Limited	No	Legacy, deprecated
WOFF	.woff	Any	Full	Yes	Compressed web font
WOFF2	.woff2	Any	Full	Yes	Better compression

Outline Types

TrueType (Quadratic Bézier)

Points connected by quadratic curves
- Simpler math
- Faster rendering (historically)
- More points needed for complex curves

CFF/PostScript (Cubic Bézier)

Points connected by cubic curves
- More elegant curves
- Fewer points needed
- Professional typography standard

OpenType Features

Modern fonts (TTF and OTF) support OpenType features:

OpenType Features:
├── Glyph substitution (GSUB)
│   ├── Ligatures (fi, fl → fi, fl)
│   ├── Small caps
│   ├── Numerals (lining, old-style, tabular)
│   └── Stylistic alternates
├── Glyph positioning (GPOS)
│   ├── Kerning
│   ├── Mark positioning
│   └── Cursor positioning
└── Layout scripts
    ├── Latin
    ├── Arabic
    ├── Devanagari
    └── Many more...

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Web Font Formats

WOFF (Web Open Font Format)

• Compressed version of TTF/OTF
• ~40% smaller than original
• Supported in all modern browsers
• Contains same data as source format

WOFF2

• Next-generation web font format
• ~30% smaller than WOFF
• Brotli compression
• Better for large font families

# Convert to WOFF2 with Fontisan
fontisan convert font.ttf font.woff2

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Font Containers

Font Container formats can hold multiple fonts in a single file, sharing common data to reduce file size.

Container Types

Container	Extension	Contents	Platform
TrueType Collection	.ttc	Multiple TTF fonts	Cross-platform
OpenType Collection	.otc	Multiple OTF fonts	Cross-platform
Data Fork Font	.dfont	Multiple fonts	macOS legacy
Font Suitcase	(no extension)	Multiple fonts	Classic Mac OS

When Containers Are Used

Containers reduce file size by sharing common tables:

# Separate files (duplicated tables)
font1.ttf (glyf, head, hmtx, loca...) = 200KB
font2.ttf (glyf, head, hmtx, loca...) = 200KB
Total: 400KB

# TTC container (shared tables)
fonts.ttc (shared: glyf, head...) = 300KB
Savings: 25%

Common Container Files

Font Family	Container	Fonts Included
Segoe UI	segoeui.ttc	Regular, Bold, Italic, Bold Italic
Arial	arial.ttf	Multiple weights
MS Gothic	msgothic.ttc	Regular, Bold

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Working with Containers in Fontist

Installation

# Fontist handles containers automatically
fontist install "Segoe UI"

Status Check

fontist status "Segoe UI"
# Returns path to TTC and internal font name

Ruby API

# Returns container info
result = Fontist::Font.find("Segoe UI")
# => { paths: ["/path/to/segoeui.ttc"], full_name: "Segoe UI" }

# The full_name identifies the font within a TTC

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Working with Containers in Fontisan

Extract from Container

# Extract individual font from TTC
fontisan extract segoeui.ttc --font "Segoe UI Bold" --output bold.ttf

Create Container

# Create TTC from multiple TTFs
fontisan create-ttf regular.ttf bold.ttf italic.ttf --output family.ttc

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Format Conversion

TTF ↔ OTF

# Convert TTF to OTF (changes outline type)
fontisan convert input.ttf output.otf

# Note: Outline conversion may affect rendering

Desktop ↔ Web

# Create web fonts from desktop fonts
fontisan convert font.ttf font.woff
fontisan convert font.ttf font.woff2

Lossless Operations

These operations preserve font data:

• TTF → WOFF → TTF (round-trip)
• OTF → WOFF2 → OTF (round-trip)
• Extract from TTC

Lossy operations:

• TTF → OTF (outline conversion)
• Subsetting (removes glyphs)
• Axis reduction (removes variable data)

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Platform Considerations

macOS

• Supports TTF, OTF, TTC, OTC
• Legacy support for dfont
• Font Book handles all formats

Windows

• Supports TTF, OTF, TTC
• Fonts in C:\Windows\Fonts
• Per-user fonts in AppData

Linux

• Supports TTF, OTF, TTC
• Uses fontconfig for discovery
• Multiple font directories

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See Also

• Fonts & Styles - Basic font concepts
• Variable Fonts - Modern variable fonts
• Fontisan Documentation - Format conversion tools