Encode and decode Base64
Turn text into Base64 and recover the original text.
Calculator inputs
Results
Enter your values and press “Calculate” to see the result.
In short
- What it calculates
- Turn text into Base64 and recover the original text.
- Formula used
Encoded size ≈ original size × 4 ÷ 3- Example
- The text “KalCum” encoded in Base64 is Q2FsY0h1Yg==
Base64 encoder and decoder
Base64 lets binary data travel through channels designed for text: HTTP headers, email attachments, tokens or images embedded in CSS.
It is not encryption: anyone can reverse it, so it never protects information.
How it works
Bytes are grouped in threes and represented by four characters of the Base64 alphabet, which grows the size by about a third.
Formula
Encoded size ≈ original size × 4 ÷ 3
Alphabet: A-Z, a-z, 0-9, + and /
Worked example
The text “KalCum” encoded in Base64 is Q2FsY0h1Yg==
The trailing equals signs are padding to complete the block.
Explanation
It is not encryption, it is encoding
Anyone can decode base64 in a second, with no key or password. Its purpose is not to hide but to transport: converting binary data into printable characters so it survives systems designed only for text. Storing a password in base64 is storing it in the clear with a transparent disguise.
Why it exists
Email was designed for seven-bit text. Sending an image or attachment through that channel required representing it with safe characters, and that is where base64 came from. The same need reappears today in tokens, certificates, images embedded in HTML and data fields in JSON.
The one-third overhead
Every three bytes become four characters, so the result takes roughly thirty-three per cent more space than the original. That is why embedding large images as base64 inside a web page can weigh more than serving them as separate files.
The equals sign padding
The equals signs at the end are not data: they pad out the final block of four characters. Their number indicates how many bytes were left over, which is why you see zero, one or two, never three.
Frequently asked questions
Is Base64 encryption?
No. It is a reversible encoding with no key. Anyone can decode it, so it protects nothing.
Why does it take more space?
Because every three original bytes become four characters, an increase of roughly 33%.
Can I use base64 to protect data?
No. It is a reversible encoding with no key that anyone can undo instantly. To protect data you must encrypt it.
Why does my string end in equals signs?
They are padding to complete the final block of four characters, indicating how many bytes were missing. There are never more than two.
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