Base64 to Decimal Converter
Decode Base64 strings to Byte Arrays or Big Integers.
About the Base64 to Decimal Converter
This tool allows you to convert Base64 encoded data back into its decimal representation. Base64 is a way of representing binary data using text characters (A-Z, a-z, 0-9, +, /). When you decode it, you essentially get the original binary numbers back.
We offer two ways to view this data: as a sequence of Bytes (numbers from 0 to 255), which is great for inspecting file headers or binary streams, or as a Big Integer, which takes the entire string and calculates its massive decimal value—useful for cryptographic keys and large identifiers.
How to Use the Tool
- Paste your Base64 string into the "Input Base64" box on the left.
- Select your desired "Conversion Mode":
- Byte Array: Shows the value of each individual byte (e.g., 72 101 108...).
- Big Integer: Converts the whole data blob into one large number.
- If using Byte Array mode, you can choose a "Separator" like spaces or commas to format the list.
- The decimal result will appear instantly in the right panel.
Frequently Asked Questions
What is the difference between Bytes and BigInt?
A "Byte Array" conversion breaks the data down into 8-bit chunks (0-255). This is how computers store files and images. A "BigInt" conversion treats the entire string as one single number. For example, the Base64 "AQ==" is byte [1] or BigInt 1.
Does this support URL-safe Base64?
Yes. Standard Base64 uses `+` and `/`, while URL-safe Base64 uses `-` and `_`. Our tool automatically detects and handles both formats correctly.
Is there a limit to the length?
Technically, no. Since we use the browser's native `BigInt` support, we can handle arbitrarily large numbers, far exceeding the standard 64-bit integer limit found in many calculators.
Is my data private?
Yes. All decoding and conversion happen entirely within your web browser via JavaScript. No data is ever sent to our servers.