Two font formats, one visual result
OpenType (.otf) and TrueType (.ttf) are both wrappers around the OpenType specification and, for the vast majority of fonts, render pixel-for-pixel identically on screen. The difference that actually matters is invisible until something rejects one of them: OTF stores its letterforms as PostScript-style Bézier outlines, TTF stores them as its own quadratic-spline outline format, and a surprising number of older tools and rigid upload forms only accept one of the two.
Where the difference actually bites
| Situation | Usually wants |
|---|---|
| Older Windows software, some legacy design tools | TTF |
| Print and professional design workflows historically | OTF |
| Embroidery and cutting-machine software | TTF, often specifically |
| Web fonts (@font-face) | Neither directly — convert to WOFF2 instead, which both can produce |
| Most modern software (current macOS, Windows, Office, browsers) | Both work interchangeably |
If a piece of software rejects your font with no useful error message, trying the other container format is a fast, low-cost thing to test before assuming the font file itself is broken.
What survives the conversion, and what does not
- Letterforms and spacing convert essentially exactly — the shapes are re-described in the other outline format without visually changing.
- OpenType features — ligatures, alternate characters, small caps and similar advanced typographic features — are frequently tied to the OTF container specifically, and support for them in software that only reads TTF can be inconsistent. A plain, feature-light font converts cleanly; a font that leans heavily on OpenType features may lose access to some of them in software with weak TTF feature support, even though the base letterforms are unaffected.
- Licensing terms travel with the font, not the container, and are unaffected by which format you use — but converting a font whose licence restricts modification or redistribution is still worth checking against that licence before doing, since a format change is a modification in the eyes of some licences even when it changes nothing visible.
When to reach for a different conversion instead
- Putting a font on a website. Neither OTF nor TTF is the right web format — both are large and neither compresses well for delivery. WOFF2 is smaller and what current browsers actually expect; most font tools that read OTF or TTF can also export WOFF2 directly.
- A font that only exists as an image or a hand-drawn alphabet. Converting a font container does nothing here — that is font creation, an entirely different and much larger undertaking involving dedicated font-design software.
Frequently asked questions
Will the font look any different after converting?
No — the letterforms are redrawn in the other outline format but describe the same visual shapes. Any visible difference points to a problem with the conversion, not an expected trade-off.
Why does my software still reject the converted file?
The problem may not be the container format at all — check for a corrupted source file, an unsupported font version, or a licence restriction some software checks for.
Is TTF or OTF 'better' in general?
Neither, for ordinary use — they are two containers for the same underlying idea, and modern software reads both interchangeably. The right one is whichever the destination software actually asks for.
Can I convert a font I downloaded for free back and forth freely?
Check its licence. A free font is not automatically free to modify or redistribute in a different format — some licences explicitly restrict that.
Does this work for variable fonts?
Variable fonts (with adjustable weight, width or other axes) are more complex, and conversion tools vary in how completely they preserve every axis. Check the result carefully if the font relies on variable axes.
Is my font file uploaded anywhere?
No. The conversion runs in your browser.