Developer Bases

Decimal to hex

Decimal value

Hexadecimal FF

Divide by 16, keep the remainders

The same number elsewhere

Decimal 255

Binary 11111111

Binary, grouped 1111 1111

Octal 377

Bits needed 8

Note

Divide by 16, read remainders backwards

The same number in each base

Decimal	Binary	Octal	Hex
0	0	0	0
1	1	1	1
8	1000	10	8
10	1010	12	A
15	1111	17	F
16	10000	20	10
64	1000000	100	40
100	1100100	144	64
255	11111111	377	FF
256	100000000	400	100
1024	10000000000	2000	400
65535	1111111111111111	177777	FFFF

To convert decimal to hexadecimal, divide repeatedly by 16 and read the remainders backwards. 255 gives 15 remainder 15, which is F and F — so FF. Values 10 to 15 are written A to F.

How to convert decimal to hex

1 Enter the decimal number.

2 Read the hexadecimal result.

3 Compare against the binary and octal forms.

4 Prefix with 0x if you are pasting it into code.

The repeated-division method works for any base and is worth understanding rather than memorising. Divide by the target base, note the remainder, divide the quotient again, and continue until the quotient is zero — then read the remainders bottom to top. It is the same procedure whether you are going to base 2, 8, 16 or 36; only the divisor changes.

Questions

What is 255 in hex? −

FF. It is the maximum value of one byte.

How do I convert by hand? +

What is 1000 in hex? +

Should I use uppercase or lowercase? +

How many hex digits do I need? +

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