Turn OTF files into WOFF
This makes a WOFF out of the OTF you already have. WOFF is the usual choice for web font delivery to browsers that predate WOFF2 support. Your file never leaves your computer.
Need the other direction? Convert WOFF to OTF
How to convert OTF to WOFF
- 1 Drop your OTF .otf file onto the page, or click to browse for it.
- 2 Check the options. Nothing is thrown away on the way to WOFF, so there is no quality dial to set.
- 3 Convert. The work happens on your own machine, so how long it takes depends on your computer and the file.
- 4 Download the WOFF, or add more files and do the whole set in one go.
Why convert OTF to WOFF
- Roughly 40 percent smaller than the TTF or OTF it wraps.
- Supported by every browser including Internet Explorer 9.
- Web font delivery to browsers that predate WOFF2 support.
- OTF: can render a little less crisply than TTF on low resolution screens.
OTF compared with WOFF
How the two formats differ on the things that decide whether a conversion is worth making.
| Property | OTF | WOFF |
|---|---|---|
| File extension | .otf | .woff |
| Compression | Uncompressed | Lossless |
| Colour depth | CFF cubic or TrueType quadratic outlines, GSUB and GPOS layout tables | Per-table zlib compression over a TrueType or OpenType payload |
| Typical file size | Largest | Larger |
| Introduced | 1996 | 2009 |
| Developed by | Microsoft and Adobe | Mozilla, Type Supply and LettError, standardised by W3C |
Quality and what changes
Both sides are lossless, so every pixel survives the trip intact and converting back returns the same image. What changes is the size and what the file can carry: WOFF compresses the same data with a different algorithm, so the size can move in either direction.
- One WOFF limitation to keep in mind: not installable as a desktop font without converting it back.
Questions about OTF to WOFF
Is my OTF file uploaded anywhere?
No. The whole thing runs inside the browser tab you already have open. Your OTF is read straight from your own disk, converted on your machine and handed back as a WOFF. Nothing is sent anywhere, nothing is stored and there is no account.
Is there a file size limit?
There is no server-side limit because no server sees the file. The real ceiling is your device memory, since the input and the output both have to fit in the tab. A few hundred megabytes is usually fine on a desktop machine and considerably less on a phone.
Can I convert several OTF files at once?
Yes. Add as many as you like and they are processed one after another, then offered as separate WOFF downloads or as a single ZIP. Speed depends on your own processor rather than on a queue.
Does the converter work offline?
Yes, after the page has loaded once. The engine is cached by the browser, so you can disconnect, reload and keep converting. That falls out of doing the work locally rather than being a separate mode you switch on.