Bidirectional conversion between Base85 (Ascii85-style) and decimal with detailed steps
Input Value
Result
Conversion Result
Step-by-Step Derivation
Base Conversion Principle
Base85 → Decimal: (charCode - 33) × 85ⁿ and sum
Decimal → Base85: Repeated division by 85, +33 (reverse remainders)
Alphabet: ASCII 33 (!) to 117 (u)
Ascii85 (Base85) is a binary-to-text encoding developed by Adobe. It uses 85 ASCII characters from 33 (!) to 117 (u), making it about 20% more efficient than Base64. Commonly used in PDF files and PostScript.
⚠Ascii85 uses ASCII characters from 33 (!) to 117 (u). To get the numeric value of a character, subtract 33 from its ASCII code. This tool demonstrates Base85 as a positional number system. Real Ascii85 encodes 4 bytes into 5 characters.
What Is Ascii85?
Ascii85, also known as Base85, is a binary-to-text encoding scheme developed by Adobe. It uses 85 ASCII characters from 33 (!) to 117 (u), making it about 20% more efficient than Base64. Ascii85 is commonly used in PDF files, PostScript, and Adobe applications.
More Efficient Than Base64
Ascii85 is about 20% more efficient than Base64. It encodes 4 bytes into 5 characters instead of 4 bytes into 6 characters like Base64.
Place Value Expansion
Base85 to decimal: (charCode - 33) × 85^position. For example, !A8 = 0×85²+32×85¹+40×85⁰ = 3160.
Repeated Division by 85
Decimal to Base85: repeatedly divide by 85, collect remainders, add 33, read in reverse.
PDF & PostScript
Ascii85 is widely used in PDF files, PostScript documents, and Adobe applications for efficient binary data encoding.
💡 Teaching Example: Convert Base85 !A8 to decimal. Place value expansion: (33-33)×85²+(65-33)×85¹+(73-33)×85⁰ = 0+32×85+40 = 2720+40 = 2760. Conversely, 2760: 2760÷85=32 r40, 32÷85=0 r32 → !A8.
Applications
PDF FilesPostScriptAdobe ApplicationsBinary EncodingCompact Data
Frequently Asked Questions
What is Ascii85 encoding?▼
Ascii85, also known as Base85, is a binary-to-text encoding scheme developed by Adobe. It uses 85 ASCII characters, making it more compact than Base64 (about 20% more efficient). Ascii85 is commonly used in PDF files, PostScript, and Adobe applications.
How do you convert Ascii85 to decimal?▼
Place value expansion: subtract 33 from each character to get its value, multiply by the corresponding power of 85, then sum. Note: This tool demonstrates Base85 as a positional number system.
How do you convert decimal to Ascii85?▼
Repeated division by 85: repeatedly divide by 85, collecting remainders. Add 33 to each remainder to get the ASCII character. Read remainders in reverse.
Why is Ascii85 used in PDFs?▼
Ascii85 is used in PDFs and PostScript because it\'s more efficient than Base64 (requires only 4/5 the space of Base64), works with 7-bit ASCII, and avoids special characters that could cause issues in text-based formats.
Free online calculators and tools covering mathematics, unit conversion, text processing, and daily life. Accurate, fast, mobile-friendly, and completely free to use.