Text to Leet Speak Converter

Leetspeak is a playful way of writing where letters are replaced with numbers and symbols that look similar. The name comes from the word elite, shortened to leet and written 1337 in leetspeak itself. It started in 1980s bulletin board systems and early hacker culture, where it worked as an in-group code, and today it is mostly used for fun in gaming usernames, memes, and retro internet jokes.

Mild replaces only the three most readable letters: A becomes 4, E becomes 3, O becomes 0, so hello world turns into h3ll0 w0rld. Full adds the rest of the classic single-character swaps: B to 8, G to 9, I to 1, K to a vertical bar plus less-than sign, L to 1, S to 5, T to 7, Z to 2, turning hello world into h3110 w0r1d. Ultra goes further with multi-character symbols for all 26 letters, for example H becomes vertical bar hyphen vertical bar and M becomes vertical bar backslash forward slash vertical bar. The full substitution chart is shown in the table above.

Not exactly, which is why this tool works one way only. Several letters share the same replacement, for example both I and L become 1, so a decoder cannot know which letter was intended. Context can guess, but a perfect automatic reversal is impossible. That ambiguity is part of what made leetspeak useful as an informal code.

Two reasons. First, each intensity level only maps certain letters: mild touches just A, E, and O, so the rest pass through. Second, you can switch any mapped letter off with the letter toggles above the output, and disabled letters are left exactly as typed. Digits, spaces, and punctuation are never converted at any level.

Yes, by default. Letters that have no leet replacement keep their original case, so HELLO becomes H3110 while hello becomes h3110. If you prefer everything lowercase, untick the Preserve case option and the input is lowercased before conversion.

It grew out of 1980s bulletin board systems and the early 1990s hacker and gaming scenes. Writing elite as 1337 marked you as an insider, and substituting symbols helped messages slip past the simple keyword filters of the era. As those communities moved onto the wider internet, the style survived as playful slang, giving us words like pwned and n00b that are still used in gaming today.

No. The conversion runs entirely in your browser with JavaScript. Nothing you type is uploaded, logged, or stored, so you can safely convert private nicknames or messages.