Input
Preparing your workspace…
How to use
- Enter binary digits, optionally beginning with 0b.
- Check the decimal result and any invalid-digit message.
- Copy the value or swap the conversion direction.
From bit positions to a decimal value
Each binary position contributes a power of two. In 101010, the set positions contribute 32, 8 and 2, giving decimal 42.
Use this tool to interpret a numeric bit string. To decode bytes that represent text, use Binary to Text instead; numeric conversion and text decoding answer different questions.
Representations and workflow
Only digits 0 and 1 belong to base two. A sign, a fraction point and underscores between digits are supported. Spaces do not join separate bytes into one number.
10101042The six binary digits describe the number 42, not a sequence of text characters.
Precision and validation
The binary fraction 0.101 is 1/2 + 1/8, or decimal 0.625. The same exact arithmetic used for integer values also handles the fractional portion.
Interpreting and reusing the result
A leading 1 does not imply a negative number here. For example, 11111111 is 255. Its signed 8-bit interpretation is −1 only when an explicit two’s-complement width is applied.
Numbers: up to 500 lines / 1 MiB, at most 4,096 characters per numeral. Fraction output: 1–128 digits. Text and byte data: 64 KiB. Bitwise operations: 8–256 bits. Workers stop after 30 seconds; inputs are not uploaded.
Frequently asked questions
Is 11111111 equal to 255 or −1?
This converter returns 255. A signed interpretation requires an explicit bit width; use the Bitwise Calculator for that.
Can I paste groups such as 1010 1010?
Use 1010_1010 for one numeric value. A space separates neither positions nor bytes in this converter.
Can this read a binary text message?
Use Binary to Text for eight-bit UTF-8 byte sequences. This page treats the entire input line as one mathematical number.
Is my input sent to a server?
No. Computation runs in a browser worker. DevToolsy does not upload or store your input.
What does Copy include?
Copy exports the selected displayed value. Download JSON preserves strings and diagnostic codes; it does not turn large numbers into floating-point values.