.afm

What is a .afm file?

Metadata for Type 1 fonts — character widths, kerning pairs, and nothing else.

Safe format
Type Font
By Adobe
MIME application/x-font-afm

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What is it

AFM (Adobe Font Metrics) is a plain-text metadata file that accompanies PostScript Type 1 fonts (.pfb/.pfa). While the PFB file contains the glyph outlines — the actual shapes of the letters — the AFM file tells applications how to use them: character widths, bounding boxes, kerning pairs, ligature definitions, and font-level metrics like ascender height and cap height.

The format is simple and human-readable. Open an AFM file in a text editor and you'll see lines like `C 65 ; WX 722 ; N A ; B 15 0 706 718 ;` — character code 65, width 722 units, name "A", bounding box coordinates. Kerning pairs appear as `KPX A V -80` — move the V 80 units left when it follows an A. It's refreshingly transparent compared to the binary tables in modern font formats.

AFM files are a relic of the Type 1 era. OpenType and TrueType fonts embed all their metrics internally — there's no sidecar file needed. You'll encounter AFMs when working with legacy publishing systems, TeX/LaTeX installations (which still use Type 1 fonts extensively), or when converting old font libraries to modern formats.

Technical details
Full Name
Adobe Font Metrics
MIME Type
application/x-font-afm
Developer
Adobe
Magic Bytes
53 74 61 72 74 (StartFontMetrics)
Safety
.afm is a known, safe format.
What opens it
Any text editor
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FontForge
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FAQ
Do I need AFM files for modern fonts?
No. OTF and TTF fonts contain all metrics internally. AFM files are only needed for PostScript Type 1 fonts (.pfb/.pfa).
Can I edit an AFM file?
Yes — it's plain text. But editing it manually is risky. If the metrics don't match the outlines in the PFB, text will be spaced incorrectly. Use FontForge for safe editing.
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