OmniCalcsBase64 Encode / Decode
Encode text to Base64 or decode it back — the classic way to transmit binary data as ASCII.
How to Use This Converter
Pick an operation, paste your input and convert. Use the URL-safe option when embedding data in URLs or file names.
- Encoding is reversible — the same alphabet decodes any valid input.
- Only valid Base64 strings can be decoded; malformed input shows an error.
Frequently Asked Questions
Is Base64 encryption?
No. It's an encoding that only transforms data; anyone can decode it instantly. Use real encryption for secrets.
Why does output get ~33% bigger?
Each 3 input bytes become 4 output characters (6 bits per character instead of 8), so the size increases by one third.
What is URL-safe Base64?
The standard alphabet uses + and / which are special in URLs. URL-safe mode swaps them for − and _ and drops padding.
Why am I getting decode errors?
Input may contain invalid characters, wrong padding, or line breaks. Some Base64 variants use different alphabets.
Practical Example
Encode the text Hello and you get SGVsbG8=. Decode SGVsbG8= and you get Hello back — encoding and decoding are exact inverses.
- Longer input:
Hello Worldencodes toSGVsbG8gV29ybGQ=. - URL-safe mode turns
+/into-_and drops the trailing=padding.
What Your Results Mean
- Padding — trailing
=characters show the final group was short and round it out to a multiple of 4. - Output length — roughly 4 characters for every 3 input bytes, so the encoded text is about 33% longer than the original.
- Decode errors — mean the input contains characters outside the Base64 alphabet, wrong padding, or unexpected line breaks.