Convert OTF to TTF

What is the difference between OTF and TTF?

Both are sfnt fonts with the same tables for character maps, metrics and OpenType features. The difference is the outlines. OpenType fonts with the .otf extension usually store them as CFF, which uses cubic PostScript curves. TrueType fonts use glyf outlines with quadratic curves. Some older software, embedded systems, game engines and font tools only accept TrueType outlines.

How to convert OTF to TTF

Drop the .otf file above and press Convert. opentype.js reads each glyph's CFF outline in your browser. Every cubic curve is replaced by one or more quadratic curves that stay within one font unit of the original, contours are turned to TrueType's clockwise direction, and new glyf and loca tables are written. All the other tables are copied as they are, so the glyph order, character map, advance widths, kerning and OpenType features such as ligatures stay intact.

What to expect

On a font with 1000 units per em, one unit is a thousandth of the font size, which is invisible at any normal size. The TTF is often 20 to 40 percent larger than the OTF, because quadratic outlines need more points. The new font has no TrueType hinting instructions, so the operating system's own rendering handles small sizes, as it does for most modern fonts. Glyph names are not stored, which matters only to font editors.

Fonts it can't convert

Variable OpenType fonts with CFF2 outlines can't be read. If you drop a font that already has TrueType outlines, it is returned unchanged with a .ttf name. WOFF and WOFF2 web fonts need to be unpacked first with WOFF to TTF or WOFF2 to TTF.

Before you start

Input: OTF and TTF. Output: TTF. The settings appear before anything runs, so you can check them first. Your original file is never changed.

Archives and fonts can hold many files or complex tables. Look over the file names you get. Don't open programs you didn't expect, and keep the source until you have checked the output.

Keep the original until you have opened and checked the result. The work happens in this browser tab, so the size you can handle depends on your device's memory, your browser and the file itself.

Steps to convert OTF to TTF

1. Drop a .otf file into the box above.
2. Press Convert to rewrite it as TrueType on your device.
3. Download the .ttf file.
4. Install or embed it wherever a TrueType font is required.