Hex to Binary

About Hex to Binary

Hex to Binary writes hex numbers as bits. Paste one, or a list of addresses, colors, masks or error codes. Each line is converted, and Steps shows each hex digit with its 4 bits.

Turn on Groups to read the bits in fours, the same way the hex digits split them. Set Signed to a width to keep every leading zero: 1A in 16 bits is 0000 0000 0001 1010.

The same tool, set up for other bases: Hex to Decimal, Decimal to Hex, Binary to Decimal, Decimal to Binary, Binary to Hex, Number Base Converter.

How to use it

1. Paste hex numbers, one per line, or load a file. Commas, tabs and semicolons also split a line, so a column from a spreadsheet works.
2. Check From and To, next to Convert. On a phone they are under More.
3. Press Convert (Alt C). Results shows every number in the To base and in decimal, hex, binary and octal. Output shows only the answers, line for line, for Copy and Download.
4. Open Steps to see the math for one number, the way you would do it on paper.
5. Swap (Alt S) puts the answers in the editor and turns From and To around, so you can check the way back.
6. In Options: Signed for two's complement, Groups for 1111 0000 or 4,294,967,295, Prefix for 0x, 0b or 0o, and how many digits a fraction gets.

How to convert hex to binary by hand

Look up each hex digit in the chart below and write its 4 bits. Put the groups together in the same order:

Hex      3     F     A     9
Bits   0011  1111  1010  1001

3FA9 = 0011 1111 1010 1001 = 11111110101001

Hex to binary chart

Hex  Binary   Hex  Binary   Hex  Binary   Hex  Binary
 0   0000      4   0100      8   1000      C   1100
 1   0001      5   0101      9   1001      D   1101
 2   0010      6   0110      A   1010      E   1110
 3   0011      7   0111      B   1011      F   1111

Negative numbers and two's complement

A hex number with a minus sign has no bits of its own until you pick a width. Set Signed to 16-bit and -1A becomes 1111 1111 1110 0110.

How two's complement works, with a table and the method by hand.

Exact for big numbers

Each hex digit maps to 4 bits, so FFFFFFFFFFFFFFFF gives 64 ones here. A converter that goes through JavaScript numbers rounds it first and gives a 1 with 64 zeros.

Why other converters round past 2^53.

Common errors

A letter that is not hex

Hex uses 0 to 9 and A to F. A G or a Z often comes from a typo, or from a number in another base. The tool marks the letter and says which base would have it.

1A3G5
G is not a hex digit. Hex uses 0 to 9 and A to F. Remove the G,
or set From to base 17 or more.

1A3F5

The letter O for a zero

Typed by hand, a capital O and a zero look the same. The tool names the letter, so you know what to type.

12O4
The letter O is not a digit. Type the digit 0 (zero) in its place.

1204

Two numbers on one line

Spaces inside a number are digit groups: 1111 0000 is one number. When the groups are not the same size, the tool still reads one number but marks the line, because it may be a list.

FF 1A 7
Read as one number, FF1A7. If these are separate numbers, put each on
its own line or split them with commas.

FF, 1A, 7

Most converters glue two lines into one number with no warning: 1F on one line and 2A on the next become 1F2A, which is 7978.

A number too big for its bits

With Signed set to a width, every number must fit in it. 8 bits are two hex digits, so a third digit is too many.

1FF (Signed: 8-bit)
1FF does not fit in 8 bits. 8 bits hold up to FF in hex.
Pick a wider Signed setting, or set it to Off.

Hex to binary in code and Excel

JavaScript  parseInt("3f", 16).toString(2)          // "111111"
            BigInt("0x" + hex).toString(2)          // any length
Python      bin(int("3f", 16))                      # '0b111111'
            format(int("3f", 16), "08b")            # '00111111'
C           printf("%lb", strtol("3f", NULL, 16))   // 111111, C23 only
Java        Integer.toBinaryString(Integer.parseInt("3f", 16))  // "111111"
Excel       =HEX2BIN("3F")                          → 111111
            =HEX2BIN("3F", 8)                       → 00111111

HEX2BIN works only up to 1FF, because the answer must fit in 10 bits. A negative number, from FFFFFFFE00 to FFFFFFFFFF, comes back as 10 bits.