Base85 / Ascii85 Encoder + Decoder
Base85 encodes binary data using printable ASCII, like base64 but denser. 4 bytes of input → 5 characters of output (vs 6 for base64), so output is ~25% smaller. Adobe's variant ("Ascii85") is used in PostScript and PDF files. This tool encodes and decodes.
How to use the Base85 / Ascii85 Encoder + Decoder
Pick encode or decode. Output updates live. Uses Adobe Ascii85 variant (no <~...~> wrappers).
Base85: more data per character
Base85 (the Adobe variant is called Ascii85) packs binary data into printable ASCII more tightly than base64. Four input bytes — a 32-bit number — become five characters drawn from an 85-symbol alphabet. Five characters can represent 855 values, just enough to cover the 232 a four-byte group needs, so the output is about 25% smaller than base64's 4-to-6 expansion.
That density is why Ascii85 appears inside PostScript and PDF files, where embedded images and fonts benefit from the smaller footprint. The trade-off is a wider character set that includes punctuation, so it is less friendly in URLs than base64url. This tool uses the Adobe alphabet without the <~ ~> wrappers and converts in both directions.
Common use cases
- PDF and PostScript internals — decode an Ascii85 stream embedded in a document.
- Compact binary text — encode data more tightly than base64 when size matters more than URL-safety.
- Inspecting embedded assets — turn an Ascii85 blob back into the bytes it represents.
- Learning the encoding — see how four bytes map to five characters and why that beats base64.
- Data interchange — move binary through a text-only channel with less overhead.