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What Base64 is for
Base64 rewrites binary data using only 64 safe printable characters, so it can travel through systems that expect text — email bodies, JSON payloads, data URIs in CSS, and HTTP headers. It is an encoding, not encryption: anyone can decode it in a second, so it protects nothing. This tool encodes and decodes in your browser.
How to use the Base64 Encoder / Decoder
- Paste your text into Input Text.
- Choose encode or decode.
- Copy the result.
- Everything runs locally — nothing is uploaded.
Formula and a worked example
3 bytes (24 bits) → 4 characters of 6 bits each · padded with '='
Because three bytes become four characters, Base64 output is about 33% larger than the input. The trailing '=' signs are padding for inputs whose length is not a multiple of three — one '=' means one leftover byte pair, two means one leftover byte.
Worked example
Hello encodes to SGVsbG8= — five bytes become eight characters plus one padding sign. Decoding Q2FsY3VsYXRvcnNTcG90 returns CalculatorsSpot.
Frequently asked questions
Is Base64 encryption?
No. It is a reversible encoding with no key. Never use it to hide passwords, tokens or personal data — anyone can decode it instantly.
Why does Base64 make data bigger?
Because every three bytes become four characters. Expect roughly a 33% increase in size.
What are the '=' characters at the end?
Padding, added when the input length is not divisible by three. They tell the decoder how many real bytes the final group holds.
Where is Base64 actually used?
Email attachments (MIME), data URIs for small images in CSS, HTTP basic authentication headers, and JSON fields that must carry binary data.
Related calculators
Other tools people use alongside the base64 encoder / decoder.