What is SFD?

Spline Font Database (SFD) is the native project file format for FontForge, an open-source font editor for font design.

What is PFM?

Printer Font Metrics (PFM) is the binary companion to PFB fonts for Windows, containing font metric data for printing.

When Should You Use SFD vs PFM?

SFD vs PFM: Key Differences

• •SFD uses lossless compression while PFM uses lossless compression — both take the same approach to file size management.
• •Since both SFD and PFM use lossless compression, the quality characteristics are comparable — differences in file size come down to how efficiently each format implements compression.
• •Transparency: N/A
• •SFD files are typically Larger than production fonts due to editing metadata while PFM files range Very small, binary format
• •Use case fit: SFD targets font design and editing, fontforge projects and PFM targets windows postscript printing, font pairing — your choice depends on which workflow stage you are serving.

Advantages of SFD

• ✓At its core, SFD relies on lossless encoding — a design choice that makes it perfect for Font design and editing, FontForge projects.
• ✓You won't run into compatibility issues with SFD — it's a universal standard across platforms.
• ✓File size management with SFD: larger files guaranteed to match the original exactly.
• ✓Every major application in the Font design and editing, FontForge projects space supports SFD natively.

Advantages of PFM

• ✓PFM compresses data using lossless methods, keeping file sizes manageable for Windows PostScript printing, font pairing.
• ✓Industry-wide support means PFM files open anywhere — from legacy systems to the latest devices.
• ✓Lossless quality makes PFM the gold standard for archival and master copies.
• ✓From professional software to open-source alternatives, PFM works out of the box.

Common Use Cases for SFD to PFM Conversion

• E-book formatting
• User interfaces
• Marketing materials
• Packaging design
• Signage systems
• Icon sets

Industry Applications

Best Practices for SFD to PFM Conversion

• →Converting SFD to PFM: check that glyph coverage is preserved — some formats have character limitations
• →Use PFM for websites where file size matters
• →Test fonts across different browsers and operating systems after conversion
• →Always keep a backup of your original files before converting
• →Choose the appropriate quality settings for your specific use case

Troubleshooting SFD to PFM Conversion

• !The converted PFM font has incorrect metrics → advance width and kerning values may differ between formats despite identical glyphs
• !PFM file looks heavier or lighter than SFD → font rendering engines handle weight and anti-aliasing differently per format
• !OpenType features (ligatures, swashes) lost after conversion to PFM → verify the target format supports advanced typographic features
• !Variable font axes missing from the converted PFM → variable font support varies significantly between formats

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