Number Base Converter

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   What’s great about our Number Base Converter

   Fast, accurate conversion of whole numbers that you can see and drag

   • Free
   • Converts binary, decimal, octal and hexadecimal instantly
   • Synced sliders and type-in boxes
   • No sign-up
   • No ads
   • Works offline once loaded
   • No daily limit
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   Type a number in any base

   Type into any box using that base’s digits (0 and 1 for binary, 0 to 7 for octal, 0 to 9 for decimal, 0 to 9 and A to F for hexadecimal), and the other boxes update instantly.

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   Or drag a slider

   Move any slider and every box shows the same number written in its own base.

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   Widen the range

   Turn on “Larger Numbers (up to 65,535)” to widen every slider’s range for much larger numbers.

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What is Number Bases?

A number base is how many digits a counting system uses. People count in base 10 (decimal), but computers work in base 2 (binary) and programmers also use base 8 (octal) and base 16 (hexadecimal) because they map neatly onto binary. This converter shows one whole number in all four.

About Binary (bin)

Binary is the base-2 number system, using only the digits 0 and 1. Computers use it because electronic circuits have two stable states, on and off.

• Each digit is a bit, and eight bits make a byte
• 1010 in binary is 10 in decimal
• Decimal 255 is 11111111 in binary, the largest 8-bit value

About Decimal (dec)

Decimal is the base-10 system used every day, with the digits 0 to 9. Each position is worth ten times the one to its right.

• It probably arose from counting on ten fingers
• 255 = 2 × 100 + 5 × 10 + 5 × 1
• The other boxes show the same number written in their own base

About Octal (oct)

Octal is base 8, using the digits 0 to 7. Each octal digit stands for exactly three binary digits.

• Octal 17 is 15 in decimal
• Unix file permissions are written in octal, such as 755
• Common in early computers whose word sizes were multiples of three bits

About Hexadecimal (hex)

Hexadecimal is base 16, using the digits 0 to 9 and the letters A to F for 10 to 15. Each hex digit stands for exactly four binary digits, so it is a compact way to write binary.

• FF in hex is 255 in decimal
• Web colors such as #FF8800 are written in hex
• Memory addresses and byte values are usually shown in hex