What is the PFM file format?
The .pfm file (Printer Font Metrics) is a binary font metrics descriptor used on Windows to define character widths, spacing, and kerning data for PostScript Type 1 fonts. Developed jointly by Microsoft and Adobe in the mid-1980s, .pfm files served as the Windows counterpart to Adobe's plain-text .afm (Adobe Font Metrics) format.
A .pfm file is always paired with a .pfb (Printer Font Binary) file - both must be present to install a Type 1 font on Windows. Adobe Type Manager (ATM) reads the .pfm to render Type 1 fonts on screen at any size. The file begins with a fixed 66-byte PFMHEADER structure containing fields such as dfVersion, dfSize, dfCopyright, dfType, and display resolution values, followed by variable-length extension blocks for the device name, face name, and kerning pair table.
Although .pfm files are rarely needed today - OpenType and TrueType fonts carry their own metrics internally - legacy prepress workflows, older print spoolers, and some PostScript RIPs may still reference them. FontForge can read and export .pfm files for conversion or inspection. The format was effectively obsoleted when Windows Vista deprecated ATM and native OpenType support became standard.
Security & safety
RISK: LOWPFM is a static metrics file with no executable code. Risk is negligible; malformed files may cause font rendering errors but no known exploit vector.
Format details
in a nutshell- Portable Float Map image - HDR floating-point image format (.pfm) used in computer graphics / tone-mapping research, unrelated to fonts.
Programs that open PFM files
Windows3 apps
Microsoft Windows Font Viewer
Built-in Double-click the PFM file - Windows may preview basic font info if ATM or compatible shim is present; limited support on Windows 10/11. 
Adobe Photoshop
Paid Photoshop uses installed Type 1 fonts system-wide; install the PFM+PFB pair via Windows Font settings first. 
FontForge
Open-source File → Open, select the .pfm file to view/edit metrics. FontForge can also generate PFM from other font formats. Technical details
deep spec| File encoding | Binary, little-endian |
| Magic bytes | First 2 bytes `0x00 0x01` (`PFMHEADER` `dfType` field); not unique on its own |
| PFMHEADER size | Fixed 66 bytes |
| Key header fields | `dfVersion`, `dfSize`, `dfCopyright`, `dfType`, `dfPoints`, `dfVertRes`, `dfHorizRes` |
| Format versions | `dfVersion` `0x0100` (Windows 3.0); `0x0200` (Extended PFM with kerning support) |
| Typical file size | 2 KB - 20 KB |
| Required companion file | Always paired with `.pfb` (Printer Font Binary); both must be present to install a Type 1 font on Windows |
| Platform | Windows only (macOS and Unix used the text-based `.afm` format instead) |
| Used by | Adobe Type Manager (ATM) to enable on-screen rendering of Type 1 fonts at arbitrary sizes |
| Structure | Fixed 66-byte `PFMHEADER` + variable extension blocks for device name, face name, and kerning pair table |
| MIME type | application/octet-stream (no dedicated MIME registered) |
| Superseded by | OpenType (`.otf`) and TrueType (`.ttf`) embed their own metrics; PFM obsolete since Windows Vista deprecated ATM |
| Released | 1985 (Windows 1.0 / early PostScript era) |
| Latest version | Windows 3.1 Printer Font Metrics spec (1992) |
PFM conversions
Community Q&A
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