Number Base Converter Free Online Tool 2026

Last updated March 22, 2026

Number Base Converter Examples

The Number Base Converter converts numbers between binary, octal, decimal, hexadecimal, and any custom base from 2 to 36. Below are examples of common conversions.

Decimal to All Common Bases

Input: 255 (decimal)

Binary (base 2):      11111111
Octal (base 8):       377
Decimal (base 10):    255
Hexadecimal (base 16): FF

Input: 1024 (decimal)

Binary:      10000000000
Octal:       2000
Decimal:     1024
Hexadecimal: 400

Step-by-Step: Decimal to Binary

Convert 42 to binary:

42 ÷ 2 = 21 remainder 0
21 ÷ 2 = 10 remainder 1
10 ÷ 2 =  5 remainder 0
 5 ÷ 2 =  2 remainder 1
 2 ÷ 2 =  1 remainder 0
 1 ÷ 2 =  0 remainder 1

Read remainders bottom to top: 101010

42 decimal = 101010 binary

Step-by-Step: Binary to Decimal

Convert 101010 to decimal:

Position: 5  4  3  2  1  0
Bit:       1  0  1  0  1  0
Value:    32  0  8  0  2  0

32 + 8 + 2 = 42

101010 binary = 42 decimal

Hexadecimal Conversions

Hex → Decimal:
  FF     = 255
  1A     = 26
  DEAD   = 57,005
  CAFE   = 51,966
  0x1F4  = 500

Decimal → Hex:
  16     = 10
  256    = 100
  65535  = FFFF
  16777215 = FFFFFF

CSS Color Code Decoding

#FF5733 decoded:
  R = FF = 255
  G = 57 = 87
  B = 33 = 51

  RGB(255, 87, 51) — a warm orange-red

#3B82F6 decoded:
  R = 3B = 59
  G = 82 = 130
  B = F6 = 246

  RGB(59, 130, 246) — Tailwind blue-500

Two's Complement (Negative Numbers)

-1 in 8-bit two's complement:
  Step 1: 1 in binary = 00000001
  Step 2: Invert bits  = 11111110
  Step 3: Add 1        = 11111111

  -1 = 11111111 (binary) = FF (hex)

-128 in 8-bit two's complement:
  = 10000000 (binary) = 80 (hex)

Range for 8-bit signed integer: -128 to 127

IP Address Binary Representation

192.168.1.1 in binary:

192 = 11000000
168 = 10101000
  1 = 00000001
  1 = 00000001

Full binary: 11000000.10101000.00000001.00000001

Subnet mask /24 = 255.255.255.0
Binary:          11111111.11111111.11111111.00000000

ASCII / Unicode Code Points

Character → Code Point:
  'A' = 65 decimal = 41 hex = 1000001 binary
  'a' = 97 decimal = 61 hex = 1100001 binary
  '0' = 48 decimal = 30 hex = 110000 binary
  '€' = 8364 decimal = 20AC hex
  '😀' = 128512 decimal = 1F600 hex (U+1F600)

Custom Base Conversions

Base 12 (duodecimal):
  12 decimal = 10 (base 12)
  144 decimal = 100 (base 12)

Base 36 (alphanumeric):
  35 decimal = Z (base 36)
  36 decimal = 10 (base 36)
  1000 decimal = RS (base 36)

Base 60 (sexagesimal — used in time/angles):
  3600 decimal = 1:0:0 (1 hour = 60 minutes × 60 seconds)

Common Use Cases

• Converting decimal values to binary for bitwise operations
• Decoding CSS hex color codes to RGB values
• Reading memory addresses and binary file formats in hex
• Understanding IP addresses and subnet masks in binary
• Learning number systems for computer science courses
• Converting ASCII and Unicode code points
• Working with embedded systems and low-level programming

Enter any number in any base and get instant conversions to binary, octal, decimal, and hexadecimal, with step-by-step explanations of the conversion process.