Why does encoded text look longer than the original?

Base64 represents 3 bytes of data using 4 characters, so encoded output is roughly 33% larger than the original — the tradeoff for representing arbitrary data as printable text.

Can I encode images or files, not just text?

This tool works on text input; encoding binary files like images typically needs a file-upload-based tool instead.

What characters appear in Base64 output?

Uppercase and lowercase letters, digits 0-9, plus + and /, with = used as padding at the end — 65 characters total including the padding symbol, per the standard alphabet.

Is Base64 the same everywhere?

The core alphabet is standardized, but a URL-safe variant replaces + and / with - and _ to avoid conflicts in URLs and filenames — this tool uses the standard (non-URL-safe) alphabet.

All tools

Developer

Base64 Encoder / Decoder

Encode or decode text as Base64.

🔒 Runs entirely in your browser — nothing here is ever uploaded

About the Base64 Encoder / Decoder

Encodes text into Base64, a way of representing binary or text data using only 64 printable ASCII characters, or decodes Base64 back into readable text.

How to use it

Choose Encode or Decode mode.
Enter your text in the Input field.
Read and copy the result below.

Formula

Encoding converts each group of 3 bytes into 4 Base64 characters using a 64-character alphabet. Decoding reverses the process.

Worked example

"Hello, CalcoTools!" encodes to SGVsbG8sIENhbGNvVG9vbHMh.

Recommendations

• Base64 is encoding, not encryption — anyone can decode it back to the original, so it doesn't provide security or privacy on its own.
• It's commonly used to embed binary data, like small images, directly inside text-based formats like JSON, HTML, or CSS.
• If decoding fails, check for accidental extra whitespace or line breaks in the encoded input.

Frequently asked questions

No — it's a reversible encoding scheme for representing binary data as text, not a security mechanism. Anyone with the string can decode it without a password or key.

Related tools

JSON Formatter

Hash Generator

Check Digit Validator

Sources

RFC 4648 — The Base16, Base32, and Base64 Data Encodings — accessed 2026-08-20