Quoted-Printable Encoder/Decoder - RFC 2045 QP Online

Quoted-Printable Encoder / Decoder

Quoted-Printable (QP) is a MIME content-transfer encoding defined in RFC 2045. It is designed for data that is mostly US-ASCII but contains occasional non-ASCII or control characters. Each non-printable byte is replaced with =XX where XX is the uppercase hexadecimal value of the byte.

Line length

RFC 2045 mandates that encoded lines must not exceed 76 characters. Longer lines are broken with a trailing = followed by CRLF: a "soft line break". When decoded the soft break is simply discarded.

Compared to Base64

Quoted-Printable is most efficient when the data is predominantly ASCII (the overhead for ASCII characters is zero). For binary or heavily non-ASCII data, Base64 produces shorter output because it uses a fixed 4-chars-per-3-bytes expansion rather than potentially 3 characters per byte.

Where QP appears today

Quoted-Printable appears in two main email contexts:

• Email headers (RFC 2047 encoded-word format): non-ASCII characters in Subject, From, or To headers are encoded as =?UTF-8?Q?...?=. For example, a subject line with an accented character appears as =?UTF-8?Q?Caf=C3=A9_menu?= in raw email source.
• Email bodies: a MIME part with Content-Transfer-Encoding: quoted-printable uses QP encoding for the body text. This is the most common encoding for HTML and plain-text email bodies that contain non-ASCII characters.

Decoding an email body

To decode a QP-encoded email using this tool:

1. In your email client, view the raw/source of the message.
2. Locate the MIME part header Content-Transfer-Encoding: quoted-printable.
3. Copy everything after the blank line that follows the headers — that is the encoded body.
4. Paste it into the Decode tab of this tool to recover the original text.