Base64 maps each group of three bytes into four text characters, with padding when needed. That makes the encoded payload roughly one-third larger, before any surrounding data format or line breaks.
It is useful when binary data must pass through a text-only channel, not when the goal is compression or secrecy. Large images and videos are usually better kept as files. If you are comparing sizes, include the full output and know whether you measured bytes or displayed characters. The Base64 tool can demonstrate this with harmless sample data.
Anyone can decode the result; it is not encryption.
The exact Base64 length is 4 × ceil(bytes / 3), before any data-URI prefix or JSON escaping. That is why the usual overhead approaches 33% for larger inputs and can be proportionally worse for tiny ones. Base64 is an encoding, not compression or encryption. If transport size matters, compress the original binary first and encode only when the surrounding protocol truly requires text.
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