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Number Base — Free Online Tool
Programmers, electronics students and networking learners constantly switch between number systems. This number base converter takes a number written in binary, octal, decimal or hexadecimal and shows its value in any of the other three. Type the number, choose the base it is written in, choose the base you want and the answer appears immediately, in uppercase for hex. Binary 1010 becomes 10 in decimal and A in hexadecimal, while decimal 255 becomes FF in hex and 11111111 in binary. The tool is useful when reading memory addresses, setting file permissions in Linux (octal 755 or 644), working with colour codes, studying digital logic, solving computer science homework and preparing for exams such as GATE where base conversion questions are common. Digits must be valid for the base you select, so a binary number can contain only 0 and 1 and an octal number only 0 to 7; otherwise the result shows NAN or stops reading at the first invalid digit. The converter works with whole non-negative numbers and relies on standard JavaScript integer handling, which is exact up to 9,007,199,254,740,991. For longer values, use a big-integer library. Everything is computed in your browser instantly with no sign-up. To convert full text strings to binary, use the Binary Translator.
Use our Number Base on AllConvertor — no registration, no download, works on iPhone, Android, Windows, and Mac. All processing runs in your browser when possible for maximum privacy and speed.
How to use Number Base
- Type the number you want to convert.
- Select the base it is currently written in.
- Select the base you want to convert to.
- Read the converted value shown below.
Key benefits
- ✓ 100% free — no paywall or trial limits
- ✓ No account or email required
- ✓ Mobile-friendly responsive design
- ✓ Instant results in your browser
- ✓ Secure — data stays on your device
- ✓ Trusted by thousands of users daily
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Frequently Asked Questions
How do I convert binary to decimal?
Choose Base 2 as the From base and Base 10 as the To base, then type the binary number. For example, 1010 gives 10.
How do I convert decimal to hexadecimal?
Set From base to 10 and To base to 16. Decimal 255 converts to FF.
Which number bases are supported?
Binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16).
Why does it show NAN or a shorter number than expected?
The digits you entered do not belong to the chosen base, for example a 2 in a binary number or a G in hexadecimal. The converter stops reading at the first invalid digit, or shows NAN if the very first character is invalid.
Is there a limit on the number size?
Whole numbers up to 9,007,199,254,740,991 (2^53 − 1) are converted exactly. Larger numbers may lose precision.