How much can subsetting reduce file size?

For CJK fonts, 90%+ reduction is common. For ASCII-only, 95%+.

What are the downsides?

Characters not included fall back to system fonts.

Is any data sent to a server?

No. Everything is processed in your browser.

Does this output WOFF2?

This tool outputs TTF. For WOFF2, use a separate tool.

Any licensing concerns?

opentype.js uses the MIT License. Check your own font license.

Font Subsetter Tool｜Subset CJK & Latin Fonts Instantly【Free】

🔒

Browser-Only Processing

Font files never leave your device

📝

No Sign-Up

No account required

⚡

High-Precision

cloud_uploadClick or drag & drop to load a font file
TTF / OTF / WOFF supported

font_download

After running subset, a preview with only the target characters will appear here

Presets (multi-select)

Additional characters

Target characters (presets + additional) — 0 chars

code

Run subset to see @font-face code

What is Font Subsetter Tool?

Web fonts enhance design quality but, especially for CJK languages like Japanese, can contain thousands of glyphs, resulting in files of several megabytes. Font subsetting extracts only the characters you actually use, dramatically reducing file size.

This tool uses opentype.js (MIT License) for high-precision subsetting entirely in your browser—no server upload required.

Key Features

✂️ Extract only needed characters to reduce file size
📂 TTF / OTF / WOFF input support
📋 Preset character sets (ASCII, Latin Extended)
👁️ Real-time preview with subset font
📊 Reduction rate and glyph count visualization
🔒 All processing in your browser

How to Subset a Font

Step 1: Upload Font

Upload a TTF, OTF, or WOFF font file.

Step 2: Enter Characters

Choose a preset or type the characters you need directly.

Step 3: Run Subset

Click "Run Subset" to process, preview, and download.

What is Font Subsetting?

Font subsetting removes unused glyphs from a font file, reducing its size. For CJK fonts, this can achieve 90%+ reduction.

Font Format Comparison

Format	Compression	Browser Support	Recommended Use
TTF	None	All Browsers	Desktop / Fallback
OTF	None	All Browsers	Desktop / Print
WOFF	ZLIB	All Browsers	Web (Legacy)
WOFF2	Brotli	Modern Browsers	Web (Recommended)

Frequently Asked Questions

Q. How much can subsetting reduce file size?: A. For CJK fonts, 90%+ reduction is common. For ASCII-only, 95%+ is possible.
Q. What are the downsides of subsetting?: A. Characters not included will fall back to system fonts. Be careful with dynamic content.
Q. Is any data sent to a server?: A. No. opentype.js processes everything in your browser.
Q. Does this output WOFF2?: A. This tool outputs TTF. For WOFF2 conversion, use a separate tool.
Q. Any licensing concerns?: A. opentype.js uses the MIT License. Check your font's own license terms separately.

Font Subsetting Use Cases

🌐

Web Performance

Subset CJK web fonts to drastically improve LCP/FCP/CWV scores.

📱

Mobile Apps

Minimize bundled font size to reduce app download size.

📧

HTML Emails

Optimize embedded fonts with limited character sets.

🎮

Games & Digital

Bundle only needed characters for faster load times.

Web Development

Font Subsetting Tool｜Reduce Web Font Size for Faster Sites