What is the TTC file format?
A .ttc file is a TrueType Font Collection - a container that bundles multiple TrueType or OpenType font faces into a single file, allowing them to share common glyph and layout tables. This sharing is most valuable for CJK (Chinese, Japanese, Korean) fonts, where two or three typeface variants - for example Regular, Bold, and a proportional cut - may share tens of thousands of identical glyphs, yielding significantly smaller combined file sizes compared to shipping separate .ttf files.
The format is identified by the four-byte magic signature ttcf at the start of the file. TTC version 1.0 stores a font count and an array of offsets pointing to each individual font's data. Version 2.0 (part of the OpenType 1.9.1 specification) adds an optional DSIG table for a digital signature covering the entire collection.
Windows ships several .ttc files as standard system fonts: msgothic.ttc bundles MS Gothic, MS PGothic, and MS UI Gothic; msmincho.ttc bundles MS Mincho and MS PMincho. macOS uses the format for the Hiragino typeface family. All major platforms - Windows, macOS, Linux, iOS, and Android - support .ttc natively.
Individual font faces can be extracted as standalone .ttf files using tools such as FontForge or the Python fonttools library. When installing a .ttc under Windows, the built-in Font Viewer lists each contained face separately.
Security & safety
RISK: LOWFont files including TTC can in principle exploit font rendering vulnerabilities (historical CVEs in Windows and FreeType), but the risk from TTCs specifically is very low in 2024+. Patched systems are not at meaningful risk from font files. The main concern is downloading fonts from untrusted sources.
Format details
in a nutshellPrograms that open TTC files
Windows3 apps
FontForge
Open-source File > Open the .ttc - FontForge prompts which font in the collection to open/edit. Can extract and export individual faces as .ttf or .otf. 
Microsoft Windows (built-in)
Built-in Double-click the .ttc - Windows Font Viewer shows the fonts in the collection. Click 'Install' to install all faces. Right-click the file > Install also works.
Microsoft Windows Font Viewer (Store app)
Free Microsoft Store font preview app - install from the Store, then open .ttc files for preview. 
macOS2 apps
Font Book (built-in)
Built-in Double-click the .ttc to open in Font Book. Click 'Install Font' to install all faces in the collection. 
Linux2 apps
FontForge
Open-source File > Open the .ttc - select which font in the collection to open. Best tool for viewing, editing or extracting individual TTF faces.
fontTools (Python library)
Open-source ttx -t TTC font.ttc - extracts individual fonts; or use fonttools.ttLib for programmatic access. Install via pip install fonttools. Technical details
deep spec| Magic bytes | ttcf (hex 74 74 63 66) at offset 0 |
| Byte order | Big-endian (all OpenType/TrueType tables use network byte order) |
| Container | TTC header wrapping multiple complete sfnt (TrueType/OpenType) font units with shared table data |
| Compression | None (raw font data; WOFF2 provides compression for web delivery) |
| MIME type | font/collection |
| Header versions | TTC 1.0 (font count + offset array); TTC 2.0 adds optional DSIG digital-signature table |
| Integrity | Per-table checksum (head.checkSumAdjustment) in each font; optional whole-file DSIG signature in TTC v2.0 |
| Max glyphs per font | 65,535 (maxp.numGlyphs field) |
| Typical file size | 1 MB - 30 MB (CJK collections at the upper end; Latin collections typically 1-5 MB) |
| Primary use | CJK font families where multiple faces share large common glyph sets (glyf, loca, cmap, GSUB, GPOS tables) |
| Table sharing | Multiple font faces within one TTC reuse identical binary glyph and layout tables, reducing total file size significantly |
| Platform | Windows, macOS, Linux, iOS, Android |
| Released | 1994 (TrueType Collections introduced in Apple's TrueType specification; widely used in Windows 95+) |
| Latest version | OpenType 1.9.1 (2023) - TTC header version 2.0 supports DSIG table for digital signatures |
| Open standard | Yes · royalty-free |
| Specification | learn.microsoft.com |
TTC conversions
Community Q&A
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