Back to Tools
File Encoding/Decoding
About Base64 Encoding
What is Base64?
Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format. It uses 64 printable characters (A-Z, a-z, 0-9, +, /) to encode data.
How it Works
Base64 takes groups of three bytes (24 bits) and converts them into four printable characters. Padding characters (=) are added when the input length is not divisible by 3.
Common Uses
- Email attachments (MIME)
- Data URLs in web pages
- API authentication tokens
- Storing binary data in text formats
- Embedding images in CSS/HTML
Base64 Reference
Character Set
0-25: A-Z
26-51: a-z
52-61: 0-9
62: +
63: /
Padding: =
26-51: a-z
52-61: 0-9
62: +
63: /
Padding: =
Size Calculation
Encoded size: ⌈(input_bytes × 4) / 3⌉
Example: 100 bytes → 134 characters
Overhead: ~33% size increase
Important Notes
- Case-sensitive encoding
- Whitespace is ignored during decoding
- Invalid characters cause decode errors
- Not suitable for encryption/security
- URL-safe variant uses - and _ instead of + and /