When is Quoted-Printable used instead of Base64?

Quoted-Printable is used when the data is mostly ASCII text with only a few non-ASCII characters, such as an English email with a couple of accented names. It keeps the body human-readable, whereas Base64 turns even plain text into an unreadable blob and always grows by a third.

Any byte that is not safe to send literally is written as an equals sign followed by its two-digit uppercase hexadecimal value. For example a non-breaking space (0xA0) becomes =A0. The equals sign itself is always escaped as =3D so it is never ambiguous.

What is a soft line break?

Email limits lines to about 76 characters. When a line would exceed that, Quoted-Printable inserts an equals sign at the very end of the line followed by a CRLF. That trailing equals is a soft break: the decoder removes it and joins the line back together, so it does not add a real newline.

Why are trailing spaces escaped?

Mail servers often strip whitespace at the end of a line, which would silently change the message. To protect them, a space or tab that falls right before a line break is encoded as =20 or =09 so it survives transit exactly.

Does this tool send my data anywhere?

No. All encoding and decoding, including UTF-8 handling, runs locally in your browser. Nothing is uploaded.

Quoted-Printable Encoder/Decoder

Quoted-Printable is the MIME encoding that keeps a mostly-text email readable while still safely carrying the occasional accented letter, symbol or 8-bit byte. This tool encodes UTF-8 text to Quoted-Printable and decodes it back, following RFC 2045, entirely in your browser.

How it works

Quoted-Printable leaves printable ASCII (33-126) untouched, with one exception: the equals sign is always written as =3D so it can never be confused with an escape. Spaces and tabs pass through except when they fall at the end of a line, where they are escaped to =20 or =09 to survive whitespace-stripping servers. Every other byte, including all multi-byte UTF-8 sequences, is written as =XX using two uppercase hexadecimal digits.

Because email lines should stay under about 76 characters, the encoder inserts a soft line break — an = at the end of a line followed by CRLF — when a line grows too long, never splitting a =XX token across the break. On decode, those soft breaks are removed and the line is rejoined, while each =XX is turned back into its byte and the result is read as UTF-8.

Tips and notes

Try encoding text with accents or emoji to see how only the non-ASCII bytes become =XX while the English words stay legible. This readability is the whole point: Quoted-Printable is ideal when a human might glance at the raw source. For attachments or heavily binary data, Base64 is more efficient, since Quoted-Printable triples the size of any byte that needs escaping.