TrueType vs OpenType vs PostScript — Font File Formats Explained
What the Differences Mean for Designers, Developers and Windows Users
Fonts come in several file formats — .ttf, .otf, .pfb, .woff, .woff2 — and choosing the right one matters depending on whether you're designing for print, screen, or the web. This guide explains what each format is, where it came from, and when to use it.
TrueType was developed by Apple in the late 1980s as a competitor to Adobe's PostScript font technology. Microsoft adopted it for Windows 3.1 in 1992, and it has since become the most common desktop font format in the world.
File extensions: .ttf (font file), .fon (older raster bitmap fonts used on early Windows)
How it works: TrueType uses quadratic Bézier curves to define the outlines of each glyph. Font files also contain "hinting" instructions — low-level code that guides the rasteriser to render glyphs crisply at small sizes on screen, especially at low resolutions.
- Pros: Excellent screen rendering at all sizes; widely supported across Windows, macOS and Linux; hinting produces good results at small point sizes.
- Cons: Limited support for advanced typographic features such as ligatures, swashes and small caps compared to OpenType.
- Windows support: Full support since Windows 3.1.
PostScript Type 1 was developed by Adobe in 1984, originally designed for laser printers. It became the professional standard for print publishing throughout the 1990s and remained widely used in prepress workflows well into the 2000s.
File extensions: .pfb (font outline data), .pfm (font metrics for Windows), .afm (Adobe Font Metrics, used on other platforms)
How it works: Type 1 uses cubic Bézier curves, which can represent outlines with slightly higher mathematical precision than the quadratic curves used by TrueType. On Windows, a Type 1 font requires both the .pfb and .pfm files to be present and registered to be usable.
- Pros: High precision for print output; superior outline quality for high-resolution devices such as imagesetters and laser printers.
- Cons: No built-in screen hinting; poor rendering at small sizes on screen; two-file requirement (.pfb + .pfm) is inconvenient; maximum of 256 characters per font face limits glyph coverage.
- Windows support: Natively supported since Windows 2000. Adobe Type Manager (ATM) was required on Windows 95/98. PostScript Type 1 support was officially removed in Windows 11 with the January 2023 cumulative update.
OpenType was developed jointly by Microsoft and Adobe in the late 1990s and released publicly in 1997. It is now the preferred professional font format for both print and screen, combining the best features of TrueType and PostScript in a single unified container.
File extensions: .otf typically indicates a file using CFF (PostScript cubic) outlines; .ttf indicates TrueType (quadratic) outlines inside an OpenType wrapper. Both are fully valid OpenType fonts — the container format is the same.
How it works: OpenType is a superset of both TrueType and PostScript. It can contain either type of outline data. What sets it apart is the OpenType Layout engine, which enables sophisticated typographic features to be embedded in the font file itself and applied automatically or on demand by supporting applications.
Advantages of OpenType:
- Single cross-platform file — one font works on Windows, macOS and Linux without conversion
- Up to 65,536 glyphs per font, compared to 256 for PostScript Type 1
- Full Unicode support — multiple languages, scripts and symbol sets in a single file
- Advanced typographic features: ligatures, small caps, old-style figures, swashes, stylistic alternates, contextual alternates, and extensive kerning pairs
- Optical size variants can be included in a single file
Limitations: Advanced OpenType features such as ligatures and stylistic alternates only activate in applications that implement the OpenType Layout engine — Adobe Creative Cloud applications, Microsoft Word, and modern browsers via CSS font-feature-settings. Basic applications will use only the base character set.
Windows support: Full support since Windows 2000.
Variable fonts were introduced in the OpenType 1.8 specification in 2016. Rather than shipping separate files for each weight and style, a single variable font file contains a continuous design space from which any point along one or more axes can be selected.
What this means in practice: Instead of installing Regular, Bold, Light, SemiBold, Italic and Bold Italic as six separate files, a single variable font can provide every weight along a continuous spectrum — including intermediate values such as weight 450 that no static file would cover.
Design axes: Standard axes include Weight (wght), Width (wdth), Italic (ital), Slant (slnt) and Optical Size (opsz). Font designers can also define custom axes for properties specific to their typeface.
File size: One variable font file typically replaces 4 to 12 static files, with a combined file size significantly smaller than the full set of static equivalents.
Examples included with Windows: Bahnschrift (Windows 10 version 1709 and later), Segoe UI Variable (Windows 11).
CSS usage: font-variation-settings: 'wght' 450;
Windows support: Supported from Windows 10 version 1709 (Fall Creators Update, 2017).
WOFF (Web Open Font Format) and WOFF2 are container formats designed specifically for delivering fonts over the web. They wrap TrueType or OpenType font data with compression and metadata, reducing download size for web pages.
WOFF (.woff): Introduced in 2010 and now supported in all browsers. A WOFF file is essentially a compressed TrueType or OpenType font with additional metadata fields for licensing information. It cannot be installed as a desktop font on Windows.
WOFF2 (.woff2): A successor format using the Brotli compression algorithm, producing files typically 30% smaller than WOFF. Supported in all modern browsers. WOFF2 is the preferred format for web font delivery.
- For web use, always serve WOFF2 as the primary format with WOFF as a fallback for older browsers.
- Do not serve raw .ttf or .otf files on the web — they are uncompressed and noticeably larger than WOFF2 equivalents.
- WOFF and WOFF2 files cannot be installed as desktop fonts on Windows — they are browser-only formats.
| Format | Extension | Curves | Max glyphs | Advanced features | Web use | Print use | Windows install |
|---|---|---|---|---|---|---|---|
| TrueType | .ttf | Quadratic | 65,536 | Limited | Not recommended | Good | Yes (since Win 3.1) |
| PostScript Type 1 | .pfb / .pfm | Cubic | 256 | None | No | Excellent | Win 2000–Win 10 only |
| OpenType (CFF) | .otf | Cubic | 65,536 | Full | Not recommended | Excellent | Yes (since Win 2000) |
| OpenType (TrueType) | .ttf | Quadratic | 65,536 | Full | Not recommended | Excellent | Yes (since Win 2000) |
| Variable Font | .ttf / .otf | Quadratic or Cubic | 65,536 | Full + axes | Possible | Excellent | Yes (Win 10 1709+) |
| WOFF | .woff | TT or OT wrapped | 65,536 | Full (if OT source) | Yes | N/A | No |
| WOFF2 | .woff2 | TT or OT wrapped | 65,536 | Full (if OT source) | Yes — preferred | N/A | No |
Use OpenType (.otf) for maximum glyph coverage, full Unicode support, and access to advanced typographic features including ligatures, small caps and stylistic alternates.
Use WOFF2 (.woff2) for the smallest file size and broadest browser support. Include a WOFF fallback for legacy browsers. Never serve uncompressed .ttf or .otf files directly on the web.
Use TrueType (.ttf) or OpenType with TrueType outlines (.ttf) — both install identically on Windows and are supported everywhere. OpenType gives you more glyphs and features if the application supports them.
Windows does not make it easy to see which format each installed font uses — the Fonts folder in File Explorer shows family names, but not the underlying format of each file. When auditing a large font library, or when you need to confirm that only licensed formats are present, you need a tool that can inspect the font files directly.
X-Fonter displays the format of every installed font and lets you filter your library by format — making it straightforward to identify which fonts are TrueType, which are OpenType, which are variable fonts, and which (if any) are the now-unsupported PostScript Type 1 format.
X-Fonter shows the format, glyph count and character coverage of every font installed on your system. Filter by format, preview any typeface in custom text, and keep your collection organised.
Learn About X-Fonter →- Fonts Included in Windows 11 — Complete font inventory for a clean Windows 11 installation
- Fonts Included in Windows 10 — Complete font inventory for a clean Windows 10 installation
- How to Manage Fonts in Windows 10 and 11 — Install, uninstall, preview and organise your font library
- Free Font Download Sites — Curated collection of free font resources