The Conversion Quality Matrix
The table below rates the most common font conversions by how much quality is preserved. "Lossless" means the output is functionally identical to the input. "Mostly safe" means outlines are preserved but some metadata or features may change. "Lossy" means visible rendering differences are possible.
| Conversion | Quality | What Changes |
|---|---|---|
| TTF → WOFF | Lossless | Just adds compression wrapper. Identical outlines and hinting. |
| TTF → WOFF2 | Lossless | Better compression than WOFF, still preserves everything. |
| OTF → WOFF2 | Lossless | CFF outlines wrapped in Brotli compression. No curve changes. |
| WOFF2 → TTF | Lossless | Decompression only. Restores original TTF if source was TrueType. |
| WOFF → WOFF2 | Lossless | Recompression with better algorithm. No data loss. |
| OTF → TTF | Mostly safe | Cubic Béziers converted to quadratic. Subtle curve differences at small sizes. Auto-hinting replaces CFF hints. |
| TTF → OTF | Mostly safe | Quadratic curves promoted to cubic (mathematically exact). But TrueType hinting is discarded. |
| Any → EOT | Lossy | Legacy format. Advanced OpenType features stripped. Only useful for IE8 and below. |
| Any → SVG Font | Lossy | No hinting, no kerning tables, massive file sizes. Effectively deprecated. |
The Curve Problem: Cubic vs. Quadratic
This is the most common source of quality loss in font conversion. OpenType fonts with CFF outlines use cubic Bézier curves (defined by 4 control points). TrueType fonts use quadratic Béziers (3 control points). Converting from cubic to quadratic requires approximation — the converter adds extra points to match the original curve as closely as possible, but it's never mathematically identical.
In practice, you won't notice the difference at body text sizes (14–18px). Where it shows up is in large display type, particularly on curves with subtle inflection points. If you're converting a font for a logo or headline use at 72px+, inspect the output carefully.
The Hinting Problem
Hinting is a set of instructions embedded in a font that tell the rasterizer how to snap outlines to the pixel grid at small sizes. TrueType and CFF use completely different hinting models, and they don't translate to each other. When you convert OTF to TTF, the CFF hints are discarded and the converter either auto-generates TrueType hints (imperfect) or leaves the font unhinted.
On modern high-DPI screens, this matters much less than it did in the era of 96dpi monitors. But if you're targeting standard-resolution displays or print, test hinting after any conversion that crosses the OTF/TTF boundary.
The Safe Path for Web Projects
If you're starting with a desktop font and need it for the web, the safest path depends on your source format. If you have a TTF, go directly to WOFF2 — it's completely lossless. If you have an OTF with CFF outlines, go directly to WOFF2 as well — the CFF outlines are preserved inside the WOFF2 wrapper. Avoid converting OTF → TTF → WOFF2, because that needlessly introduces the cubic-to-quadratic conversion in the middle.
Run a conversion at Font-Converters.com →