Numbers to Hex Converter

Fast, accurate and free online numbers to hex converter tool running directly in your browser.

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Instructions

1

Enter data
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2

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3

Get the result
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Input data

43 characters

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Result

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Decimal to HEX converter and positional systems

Positional systems are the basis of computer science: binary (2), octal (8), decimal (10) and hexadecimal (16). Each system has its own use: binary - hardware, hex - CSS colors and memory addresses, octal - Unix permissions (chmod). The converter converts between all systems.

decimal hex converter hexadecimal numbers decimal to hex octal hex binary converter

Positional systems - basics

Binary (base-2): digits 0-1. Each position = power of 2. 1010₂ = 1×8+0×4+1×2+0×1 = 10₁₀. Octal (base-8): digits 0-7. 12₈ = 1×8+2 = 10₁₀. Decimal (base-10): digits 0-9. Hexadecimal (base-16): digits 0-9, A-F. FF₁₆ = 15×16+15 = 255₁₀. Letters: A=10, B=11, C=12, D=13, E=14, F=15.

Cross-system conversion

Decimal → binary: divide by 2, get remainders. 10÷2=5 r0, 5÷2=2 r1, 2÷2=1 r0, 1÷2=0 r1 → 1010₂. Decimal → hex: divide by 16. 255÷16=15 r15 → FF₁₆. Hex → binary: each hex digit = 4 bits. F₁₆=1111₂, A₁₆=1010₂. FA₁₆=11111010₂. Octal → binary: each digit = 3 bits.

Hex in programming

CSS colors: #RRGGBB. #FF0000 = red. #00FF00 = green. #0000FF = blue. #FFFFFF = white. #000000 = black. Memory addresses: 0x7FFC1234 (prefix 0x). ASCII hex: "A" = 0x41 = 65₁₀. Unicode: U+0041. HTML entities: A = A. RGB hex colors: the tool on this page converts.

Chmod and the octal system

chmod 755: 7=rwx, 5=r-x, 5=r-x. Binary: 111 101 101. 7=111₂(4+2+1), 5=101₂(4+0+1). chmod 644: owner rw-, group r--, others r--. chmod 777: full permissions for everyone (risky!). Quick memorization: 4=read, 2=write, 1=execute. Sum = permissions.

Frequently asked questions

How to quickly convert hex in your head?

Remember: 0=0000, 1=0001, ..., 9=1001, A=1010, B=1011, C=1100, D=1101, E=1110, F=1111. Hex → decimal: F×16 + A = 15×16+10 = 250. AB₁₆ = 10×16+11 = 171. Quick: the first 256 numbers (00-FF) are worth knowing by heart as a programmer.

How is hex used in CSS colors?

#RRGGBB: R, G, B in the range 00-FF (0-255). #FF5733: R=255, G=87, B=51 = coral. Abbreviation: #FFF = #FFFFFF. Transparency: #RRGGBBAA or rgba(). Tools: color.adobe.com, coolors.co. JavaScript: parseInt("FF", 16) = 255. CSS variables: --color: #3498db.

How to convert ASCII to hex?

Each ASCII character: number 0-127 (0-255 for extended). A=65=0x41, a=97=0x61, space=32=0x20. JavaScript: "A".charCodeAt(0).toString(16) = "41". Python: hex(ord("A")) = "0x41". Entire string: "Hello".split("").map(c => c.charCodeAt(0).toString(16)) = ["48","65","6c","6c","6f"].

What is two's complement?

Representation of negative numbers in binary. For 8-bit: -1 = 11111111 = 0xFF. -128 = 10000000 = 0x80. 127 = 01111111 = 0x7F. How to calculate: reverse bits + 1. -42: 42 = 00101010, reverse = 11010101, +1 = 11010110 = 0xD6. Why: Simple addition math works without special sign handling.

What are some common hex numbers to remember?

0xFF = 255 (max byte). 0x100 = 256 (256 values per byte). 0x7F = 127 (max signed byte). 0x80 = 128. 0xFFFF = 65535 (max 2 bytes). 0xDEADBEEF: the famous debug value (0xDEAD BEEF). 0xCAFEBABE: magic bytes Java .class file. 0x1337 = "leet" (1337 speak). 0xC0FFEE: coffee.

Related tools: chmod calculator, hex color converter and ASCII encoder.