Two years into building MoFont, the question I get most isn't "does it look like my writing?" or "how much does it cost?" It's this one: "When training's done, do I get an OTF or a TTF? Which one am I supposed to use?"
Every time, I want to say "you get both, use whichever," but that's a cop-out. So here's the honest, full version — the kind that leaves you actually knowing something the next time you hit that export button, instead of picking one at random.
The short answer, in case you don't read to the end
If you just want to drop your handwriting into Word, screenshot it for a post, or print a postcard, you will barely notice any difference between these two formats. Genuinely. I've produced hundreds of handwriting fonts, and for 90% of users, the OTF and the TTF look identical on their machine.
But you asked, so I owe you a real answer. The difference exists — it's just buried in the math of the curves.
What actually differs: one uses cubic curves, the other quadratic
Every stroke outline in a font is, at bottom, a string of Bézier curves stitched together — the same kind of arc you draw in design software by dragging those two little handles.
The difference is the degree of that arc:
- OTF (specifically the CFF / PostScript outlines inside it) uses cubic Bézier curves, with two control points per segment.
- TTF (TrueType) uses quadratic Bézier curves, with just one control point per segment.
I'm not making this up. The Wikipedia OpenType article puts it bluntly: "TrueType outlines use quadratic Bézier curves" / "CFF outlines use cubic Bézier curves." Microsoft's OpenType specification confirms that a font's outline data lives either in TrueType's glyf table or in a CFF table — which is why "OTF vs TTF" is itself a bit of a shorthand. The precise question is: which flavor of outline is sitting inside the same OpenType shell.
So what does "quadratic vs cubic" mean for handwriting?
Cubic curves are more economical. A loose, free arc — say the flick at the end of a sweeping stroke, or the rounded turn where two letters connect — might take two or three cubic segments to trace, but five or six quadratic ones to approximate it. Handwriting is nothing but these wayward arcs, so purely geometrically, CFF/OTF tends to hug a handwritten stroke more closely, with fewer points, and a theoretically tighter file.
Quadratic curves win on rendering simplicity. TrueType was designed by Apple and Microsoft precisely to render crisply on screen, especially at small sizes, and it carries a powerful hinting mechanism. FontForge's glyph-math documentation even has a section on "approximating a cubic spline by a series of quadratic splines" — because converting between the two systems is a daily chore, and the tools sorted it out long ago.
In plain terms: cubic curves draw elegantly; quadratic curves run reliably. For something like a handwriting font — lots of curves, but almost nobody squinting at 12-pixel text — modern high-resolution screens have flattened that difference to near nothing.
In practice, where each one is stronger
Sorted by the scenarios users actually run into:
Where OTF fits better:
- Design software (Illustrator, Photoshop, InDesign, Figma) — the design world defaults to OTF, since it often carries more typographic features and the curves are more "native."
- Print and publishing — print shops and pro layout pipelines are more at home with PostScript outlines, and blown up to poster size, the cubic advantage finally becomes visible.
- When you want the file a touch smaller.
Where TTF is more bulletproof:
- Older Windows, certain old printers, the occasional internal corporate system — their TrueType support is in the marrow, and a TTF almost never throws a tantrum.
- The fallback for web fonts — yes, the web favors WOFF2 now, but if you must stuff a local font into a page, TTF has the highest tolerance.
- The "safe bet" when you don't know what's on the other person's computer.
As for file size and small-size rendering: for a 6,500-character Chinese handwriting font, the OTF/TTF size gap is usually a few hundred KB to a megabyte or two — not worth losing sleep over in the age of cheap storage and fast networks. And the small-size rendering difference only shows up if you shrink the text down very small and lean in close. Day to day, you won't feel it.
My honest take for a handwriting font
I do this for a living, but I'm not going to feed you "OTF is fancier, so pick OTF." The truth is:
For most people, either one is correct — because you should keep both.
My advice is simple:
- Everyday typing, messaging, Word layout — install either; every system reads them.
- Design, print, scaling up — use the OTF.
- Sending it to someone else, an unknown computer, or an old device — send the TTF; least likely to misbehave.
Which is exactly why I decided from day one: MoFont gives you both the OTF and the TTF from a single training run. Not OTF for one fee and TTF for another — they're packaged together as products of the same run. You don't have to figure out today where you'll use it later, because you'll have both in hand either way.
And while I'm being blunt, here are the lines I drew building MoFont: buy once, no subscription, no watermark. You pay once and get the OTF + TTF of your own handwriting, covering roughly 6,500 common characters — write around 30–50 characters, wait about three to four hours of training, and it's done. It's your handwriting, not a rental. The prices are all out in the open; you can take them in at a glance on the pricing page.
I learned all of this from a fairly clueless starting point — I once believed that "the model can generate pretty individual characters" was the same thing as "I made a usable font." Only later did I find out how many nights sat in between: tweaking outlines in FontForge, converting back and forth between quadratic and cubic curves, testing over and over whether the thing would even open properly in Word.
So when you ask me OTF or TTF, my answer is always: don't agonize. Take both. When the moment comes to use one, you'll just know.
— Iris
