ASCII85 (Base85) encodes binary data using 85 printable ASCII characters (! through u, plus z for all-zero groups). It produces ~25% less output than Base64.

How is ASCII85 different from Base64?

ASCII85 is more efficient — it encodes 4 bytes as 5 characters, giving ~25% overhead versus Base64's ~33%. It is used in PDF and PostScript files.

ASCII85 Encoder & Decoder — Free Online Tool

ASCII85, also called Base85, is a binary-to-text encoding scheme that represents binary data using 85 printable ASCII characters. It is significantly more efficient than Base64, producing only about 25% overhead compared to Base64's 33%. ASCII85 is used natively in PDF and PostScript file formats.

How ASCII85 Encoding Works

ASCII85 takes 4 bytes of input at a time and encodes them as 5 printable ASCII characters in the range 33–117 (! through u). As a special optimisation, a group of four zero bytes is encoded as the single character z, saving 4 characters. The encoded data is typically wrapped in <~ ... ~> delimiters in PDF files.

ASCII85 vs Base64

Base64 encodes 3 bytes → 4 characters (~33% overhead)
ASCII85 encodes 4 bytes → 5 characters (~25% overhead)
ASCII85 uses 85 printable characters; Base64 uses 64
ASCII85 is used in PDF/PostScript; Base64 is used in HTTP, email, JWT

Frequently Asked Questions

Where is ASCII85 used?

ASCII85 is used inside PDF and PostScript files to encode binary streams such as fonts and images. Adobe created Ascii85Encode and Ascii85Decode filters for this purpose.

Is ASCII85 secure?

No. ASCII85 is encoding, not encryption. Anyone can decode it instantly. Use it only for data transport, not to protect sensitive information.

What are the <~ and ~> delimiters?

These are the standard start and end markers for an ASCII85 encoded block, as defined in the PostScript Language Reference. Our tool includes them in the encoded output.

ASCII85 Encoder & Decoder online

Encode text to ASCII85 (Base85) and decode ASCII85 back to text — runs in your browser