Why does Base64 increase data size by approximately 33%?

Base64 encodes every 3 bytes (24 bits) of raw binary data into 4 ASCII printable characters (6 bits each). Because 4 bytes are used to represent what was originally 3 bytes, the encoded output is exactly 4/3 (~133.3%) of the original size.

What is URL-Safe Base64?

Standard Base64 uses '+' and '/' characters, which have special meanings in URL query strings. URL-safe Base64 (RFC 4648 §5) replaces '+' with '-' and '/' with '_', and often omits trailing '=' padding characters.

🔐 Binary Data & Cryptographic Encoding

Base64 Encoder & Decoder

Convert plain UTF-8 text to Base64 strings and decode Base64 data with full URL-safe RFC 4648 compatibility.

Enable URL-Safe Base64 (RFC 4648: - and _ without padding)

Input Text (UTF-8):

Base64 Encoded Result

SGVsbG8gV29ybGQhIPCfmYA=

Payload size: 15 bytes in, 24 bytes Base64 out (+60.0% overhead)

How Base64 Binary Encoding Works

Base64 is a binary-to-text encoding scheme designed to transmit binary data over communication channels that are exclusively designed to handle ASCII characters (such as MIME email attachments, JSON payloads, and Data URIs).

The 6-Bit Encoding Process

Standard bytes are 8 bits wide ($2^8 = 256$ possible values). Base64 divides input streams into 6-bit chunks ($2^6 = 64$ values), mapping each 6-bit integer to an ASCII index character (`A-Z`, `a-z`, `0-9`, `+`, and `/`).

Base64 Encoder & Decoder

How Base64 Binary Encoding Works

The 6-Bit Encoding Process

Related Developer Utilities

{ } JSON Formatter

🆔 UUID Generator

🔑 Password Generator