What is an OTF file?
OTF stands for OpenType font. It was created by Microsoft and Adobe and first released in 1996. OpenType extends TrueType with advanced typography such as ligatures and alternate glyphs. An .otf file usually holds PostScript-style cubic outlines rather than TrueType curves.
| Type | font |
|---|---|
| Compression | Lossless |
| In a browser | installs on Windows, Mac and Linux; browsers load it through CSS |
| Common uses | professional typography, ligatures and design work |
| MIME type | font/otf |
Which format should you convert OTF to?
- OTF to WOFF to use the font on a website.
- OTF to TTF to install the font on a computer.
How to open an OTF file
Whether an OTF file opens with a double click depends on the device. Here is what works on each, without buying software:
| Windows | Double-click a TTF or OTF to preview and install it. WOFF files are for websites and do not install. |
|---|---|
| Mac | Double-click a TTF or OTF to open Font Book and install it. |
| iPhone and iPad | Fonts install through apps or configuration profiles; the Files app can preview some. |
| Android | Most phones cannot install system fonts; apps with custom font options can use the file. |
| Web browser | OTF installs on Windows, Mac and Linux; browsers load it through CSS. |
Want the technical details? See what a .otf file is, with its MIME type, file signature and a viewer.
OTF compared with other font formats
How OTF stacks up against the formats people most often convert it to or from:
| Format | Compression | Usually contains | Released | Best for |
|---|---|---|---|---|
| OTF | Lossless | glyph outlines, usually cubic PostScript curves, plus typographic features | 1996 | professional typography, ligatures and design work |
| TTF | Lossless | glyph outlines drawn with quadratic curves | 1991 | installing fonts on a computer and embedding them in documents |
| WOFF | Lossless | the tables of a TrueType or OpenType font, each compressed | 2009 | fonts served by websites |
How to use the OTF converter
- Choose the format you want in the Convert to menu.
- Drop your OTF files on the box, or press Choose OTF files. Several files can go in at once.
- Adjust the settings if you need to; the defaults suit most people.
- Press Convert and save each file with its Download button. Converting to PNG, SVG, TTF, WOFF2 uses our server, which deletes the file right after; the rest never leave your device.
Tips for converting OTF files without losing anything
Converting an OTF file keeps the design of every glyph. Between packagings, such as WOFF, WOFF2 and EOT, the font inside is unchanged; between TrueType and PostScript outlines, the curves are redrawn with no visible difference, though hinting can change.
- Check the licence before converting a font for the web: many desktop licences do not allow web embedding.
- Serve WOFF (or WOFF2) to browsers and keep TTF or OTF for installing on computers.
- Converting between TTF, OTF, WOFF and WOFF2 keeps the design of every glyph; only a change between TrueType and PostScript outlines redraws the curves, with no visible difference.
- Subsetting a font to the characters you use is the biggest saving for web pages.
- Test the converted font in a browser page before rolling it out, to confirm every weight and style is linked in your CSS.
- Keep one family per folder with clear file names such as Brand-Bold.woff, so the right weight is always loaded.
- Variable fonts convert the same way; the axes and named instances travel with the font tables unchanged.
Convert OTF files from the command line
The fontTools library for Python converts between font and web font formats:
python3 -c "from fontTools.ttLib import TTFont; f = TTFont('input.otf'); f.flavor = 'woff'; f.save('output.woff')"The converter on this page does the same job in your browser, without installing anything.
OTF converter FAQ
What is an OTF file?
OTF stands for OpenType font, a font format created by Microsoft and Adobe in 1996. OpenType extends TrueType with advanced typography such as ligatures and alternate glyphs. An .otf file usually holds PostScript-style cubic outlines rather than TrueType curves.
How do I open an OTF file?
OTF installs on Windows, Mac and Linux; browsers load it through CSS. If the program you need will not open it, convert it to a more widely supported format above.
What is the most common OTF conversion?
OTF to WOFF is the conversion people search for most. Each table of the OTF font is compressed and wrapped in a WOFF header. The glyphs, kerning, hinting and OpenType features inside are unchanged.
Does converting OTF files here upload them?
Only for some conversions. Converting to PNG, SVG, TTF, WOFF2 uses our conversion server, where the file is deleted as soon as the result is sent back; the other conversions run inside your browser and never leave your device.
Is the OTF converter free?
Yes. There is no sign-up and no watermark. Conversions that use our server accept files up to 25 MB, with a fair-use limit per hour. The site is supported by advertising.
Can I convert OTF files on iPhone or Android?
Yes. Open this page in Safari on iPhone and iPad, or in Chrome on Android, choose your OTF files and download the results to your Downloads folder.
Can I convert several OTF files at once?
Yes. Drop as many as you like; they are converted one after another, each with its own download button.