Number base converter

Convert an integer between binary, octal, decimal, hexadecimal, and any base from 2 to 36. Type in any row — the rest update as you go.

Binary base 2

Octal base 8

Decimal base 10

Hexadecimal base 16

Custom

Binary, grouped in bytes: 1111 1111

What each base is used for

Binary — Base 2 — the two-state form every digital circuit stores.
Octal — Base 8 — still used for Unix file permissions.
Decimal — Base 10 — ordinary everyday numbers.
Hexadecimal — Base 16 — memory addresses, colour codes, and byte dumps.

Quick reference

Decimal	Binary	Octal	Hex
0	0	0	0
1	1	1	1
2	10	2	2
4	100	4	4
8	1000	10	8
10	1010	12	A
15	1111	17	F
16	10000	20	10
31	11111	37	1F
32	100000	40	20
64	1000000	100	40
100	1100100	144	64
127	1111111	177	7F
128	10000000	200	80
255	11111111	377	FF
256	100000000	400	100
1000	1111101000	1750	3E8
1024	10000000000	2000	400
4096	1000000000000	10000	1000
65535	1111111111111111	177777	FFFF

Frequently asked questions

How do I convert decimal to binary by hand?

Divide the number by 2 repeatedly, writing down each remainder. Reading the remainders from last to first gives the binary digits. For example 13 ÷ 2 = 6 r1, 6 ÷ 2 = 3 r0, 3 ÷ 2 = 1 r1, 1 ÷ 2 = 0 r1, so 13 is 1101.

Why is hexadecimal used so often in computing?

One hex digit represents exactly four bits, so a byte is always two hex digits. That makes hex a compact, lossless shorthand for binary — FF is far easier to read than 11111111.

What is the largest base this converter supports?

Base 36, which uses the digits 0–9 followed by the letters A–Z. Base 2 is the smallest. Any base in that range can be entered in the custom row.

Does this handle negative or fractional numbers?

Negative integers are supported. Fractional values are not converted, because fractions in one base often cannot be written exactly in another — one tenth is finite in decimal but repeats forever in binary.