How to Calculate Base64 Size Increase

Quick answer

Use this guide before Base64 encoding data for an API, database field, queue message, or config value. Base64 is convenient, but it usually makes data larger.

Who this is for

• Developers checking encoded payload size
• API teams working with limits
• Backend engineers storing encoded data
• Support teams explaining why encoded values grew

What to remove or avoid

• Private payload content before sharing examples
• Unneeded data before encoding
• Secrets that should not be copied into tickets

What to keep visible

• Original size
• Estimated Base64 size
• Percentage increase
• Clear result you can copy into notes

Useful controls in the tool

• Paste text or JSON.
• Review original and encoded size.
• Copy the report if needed.
• Use JSON Payload Size Calculator for JSON-specific size checks.

Step-by-step

1. 1Paste the text or JSON.
2. 2Review the original byte size.
3. 3Check the estimated Base64 size.
4. 4Compare the percentage increase.
5. 5Decide whether encoding still fits the limit.

Example

Before:
OpenBrowserTools payload example

After:
Original size, Base64 size, and percentage increase are shown in the report.

What to do after review

• Avoid Base64 when it pushes data past an API or queue limit.
• Compress before encoding only when the receiving system supports it.
• Do not share encoded secrets publicly.

Tip: Base64 is not encryption. Treat encoded secrets as exposed secrets.