Base64 Encoded Size Calculator
Base64 Encoded Size
Calculate how large data becomes after Base64 encoding
Decode Size Estimate
Estimate the original size from a Base64 encoded data length
Formula
Encoded Size = ceil(Input Bytes / 3) * 4 | Overhead = ~33.33%
Frequently Asked Questions
Why is Base64 encoding larger than the original?
Base64 encodes 3 bytes of binary data into 4 ASCII characters, resulting in a 33% size increase. This is because Base64 uses only 64 printable ASCII characters (A-Z, a-z, 0-9, +, /) to represent binary data, which is less efficient but safe for text-based protocols.
When should I use Base64 encoding?
Base64 is used to embed binary data (images, files) in text-based formats like JSON, XML, HTML, CSS, or email (MIME). It is also used in data URIs, JWT tokens, and basic HTTP authentication. Avoid it when binary transfer is possible, as it increases size by ~33%.
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