Binary numbers: Bits and place values

A byte has eight bits. Each bit has a place value. Turn bits on and off to build a number.

Number basics

Binary uses 0 and 1

A bit is one binary digit. A bit can be 0 or 1. Each place is a power of two. From right to left, the place values are 1, 2, 4, 8, 16, 32, 64 and 128.

Choose a starting number

Decimal value

You can also press any bit below. The buttons work with a keyboard.

One byte

Place values

A 1 means “include this place value.” A 0 means “add zero.” Add the included values to get decimal.

Binary and hexadecimal

Hexadecimal uses sixteen digits: 0–9 and A–F. Four bits make one hex digit. For example, 0010 1010 is 2Ah, which is 42 in decimal.

Binary	Hex	Decimal
0000 0000	00h	0
0010 1010	2Ah	42
1111 1111	FFh	255

Numbers 1 to 16 in binary

Each row shows the same value in decimal, 8-bit binary and hexadecimal. The leading zeroes fill the byte; they do not change the value.

Decimal	8-bit binary	Hexadecimal
1	0000 0001	01h
2	0000 0010	02h
3	0000 0011	03h
4	0000 0100	04h
5	0000 0101	05h
6	0000 0110	06h
7	0000 0111	07h
8	0000 1000	08h
9	0000 1001	09h
10	0000 1010	0Ah
11	0000 1011	0Bh
12	0000 1100	0Ch
13	0000 1101	0Dh
14	0000 1110	0Eh
15	0000 1111	0Fh
16	0001 0000	10h

Eight bits can show unsigned values from 0 to 255. The same byte can also represent a signed value from −128 to +127. See Negative numbers in binary and hexadecimal for the two’s-complement method.