Convert Unicode to Binary

Depends on what you’re doing. UTF-8 matches what the web uses, what most file formats store, and what most networking protocols transmit – pick this for general data interchange. Codepoint matches conceptual Unicode “characters” and is useful for teaching how Unicode works. UTF-16 matches JavaScript’s internal string representation, useful when debugging surrogate pair issues or when working with .NET / Java which also use UTF-16 internally.

Because 😀 (U+1F600) is outside the Basic Multilingual Plane (codepoint > U+FFFF). UTF-8 encodes it as 4 bytes following the standard pattern: lead byte 11110xxx + three continuation bytes 10xxxxxx. Total: F0 9F 98 80 hex or 11110000 10011111 10011000 10000000 binary – 32 bits to represent one character. That’s why emoji-heavy text feels “expensive” in bytes.

Codepoints have variable bit-width – U+0041 needs 7 bits, U+10FFFF needs 21 bits. Padding to a fixed width gives uniform output: 8 bits for ASCII-only data, 16 bits for everything in BMP (Basic Multilingual Plane covering most living languages), 21 bits for the full Unicode range, 32 bits for fixed-width storage. Without padding, the binary lengths vary character-to-character, which can be hard to parse.

Non-BMP characters (codepoint > U+FFFF, like emoji) need a surrogate pair in UTF-16 – two 16-bit code units. So 😀 becomes 11011000 00111101 11011110 00000000 (the high surrogate 0xD83D followed by low surrogate 0xDE00). Decoding reverses this: 16-bit units in the surrogate range get paired up to recover the original codepoint.

Yes – click Swap. The decoder respects the selected mode and requires the appropriate bit alignment: UTF-8 needs multiples of 8, UTF-16 needs multiples of 16, codepoint mode needs whitespace-separated groups. Specific errors point at the problem: "UTF-8 mode requires a multiple of 8 bits (got 13)", "Codepoint 1234567 exceeds U+10FFFF maximum", etc.

That sibling tool only emits UTF-8 binary. This one supports three encoding modes (UTF-8, codepoint, UTF-16) with a per-character grid showing all three side by side. Use the sibling for quick UTF-8 conversions, use this for educational comparisons or when you specifically need codepoint or UTF-16 representations.

Yes. The per-character grid substitutes visible glyphs for whitespace (space → ·, newline → ↵, tab → →) so rows aren’t blank. The actual encoded bits still represent the original characters (00100000, 00001010, 00001001 respectively). Useful when debugging mysterious whitespace differences.

200,000 characters. The per-character grid caps at 256 displayed rows with a “… N more” note, but the conversion processes the full input – only the grid display is truncated. Copy and Download give you the complete binary output.

No. All encoding (UTF-8 via TextEncoder, UTF-16 via charCodeAt, codepoint via codePointAt), binary formatting, and TSV emission run in your browser. Open DevTools → Network and confirm zero requests fire – even when you Convert or Download. Safe for sensitive text, code samples, or proprietary content.

Yes. Total bundle is about 18 KB. Load once, disconnect, keep using. Pure JavaScript with no remote dependencies. Useful for teaching Unicode encoding in classrooms without internet, or debugging encoding issues on airgapped dev machines.