Understanding Base64 Encoding
Base64 is a binary-to-text encoding scheme defined in RFC 4648. It converts arbitrary binary data—such as images, PDF files, executable code, or non-ASCII text—into a clean stream of printable 7-bit ASCII characters.
The Base64 alphabet consists of 64 standard characters: uppercase letters A-Z, lowercase letters a-z, numbers 0-9, the plus sign (+), and the forward slash (/). The equals sign (=) is reserved for byte alignment padding.
How the Base64 Algorithm Works
Standard computer systems store data in 8-bit bytes. Base64 processes data in 24-bit blocks (3 bytes at a time) and splits those 24 bits into four 6-bit segments (2^6 = 64). Each 6-bit segment maps directly to one character in the 64-character alphabet table.
Algorithm Example: Encoding "Man":
Input text: "Man"
ASCII values: 77, 97, 110
Binary representation: 01001101 01100001 01101110 (24 bits)
Split 6-bit groups: 010011 | 010110 | 000101 | 101110
Decimal indices: 19, 22, 5, 46
Base64 output: T | W | F | u → "TWFu"
Why Does Base64 Increase File Size?
Because Base64 uses 4 ASCII characters (32 bits) to represent 3 original binary bytes (24 bits), the encoded string size is always exactly 33.3% larger than the original raw data.
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