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Number System Converter

Convert between Binary, Decimal, Hexadecimal, and Octal - Edit any field to update all others

Number Converters

Tip: Type in any field and all other number systems will update automatically in real-time.

Runs in your browser

One number, four bases

Binary base 2 Decimal base 10 Hex base 16 Octal base 8

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Convert between number bases

This number base converter keeps binary, decimal, hexadecimal and octal in step: type in any of the four fields and the other three are rewritten as you type. The strip under the fields lights the ones of the number, eight bits to a byte, for values up to 64 bits.

Every field accepts the prefix programmers write in code, 0b, 0o or 0x, and ignores spaces and underscores, so 0xFF_FF or 1111 0000 can be pasted as they are. Whole numbers of any length convert exactly.

Binary, octal, decimal and hex compared

System	Base	Digits	Prefix in code	Where you meet it
Binary	2	0 1	<code>0b1010</code>	Bit flags, masks, network subnets
Octal	8	0-7	<code>0o12</code>	Unix file permissions such as `chmod 755`
Decimal	10	0-9	-	Everyday numbers, IDs, counts
Hex	16	0-9 A-F	<code>0xFF</code>	Colours like `#FF8800`, bytes, memory addresses

Octal and hex are shorthand for binary: one octal digit is exactly three bits and one hex digit exactly four, which is why a byte is always two hex digits.

Number system conversion chart

The first sixteen values, where hex runs out of single digits, and the landmarks you meet most:

Decimal	Binary	Octal	Hex
0	0	0	0
1	1	1	1
2	10	2	2
3	11	3	3
4	100	4	4
5	101	5	5
6	110	6	6
7	111	7	7
8	1000	10	8
9	1001	11	9
10	1010	12	A
11	1011	13	B
12	1100	14	C
13	1101	15	D
14	1110	16	E
15	1111	17	F
16	10000	20	10
255	11111111	377	FF
256	100000000	400	100
4096	1000000000000	10000	1000
65535	1111111111111111	177777	FFFF

Convert one way, with the steps

When you only need one direction, each pair has its own converter that also writes out the working, division by division or bit group by bit group:

From	To
Binary	Binary to decimal · Binary to hex · Binary to octal
Decimal	Decimal to binary · Decimal to hex · Decimal to octal
Hex	Hex to decimal · Hex to binary · Hex to octal
Octal	Octal to decimal · Octal to binary · Octal to hex

Number system questions

Any of them. The field you type in is the source, and the other three follow. A digit the base doesn't use, such as 2 in binary or G in hex, marks the field and leaves the others as they were.

Base 16 needs sixteen digits and there are only ten numerals, so A to F stand for 10 to 15. Upper and lower case mean the same; the converter writes upper case.

The minus sign is kept and the digits are the size of the number: -10 is -1010 in binary and -A in hex. Two's complement, the form a CPU stores, is not shown.

No practical one: the arithmetic is exact for whole numbers of any length. The bit strip shows numbers up to 64 bits.

No. The conversion runs in your browser.