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Hex Calculator

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Understanding Hexadecimal System

Hexadecimal (hex) is a base-16 number system that's everywhere in computing. While we humans use decimal (base-10) with digits 0-9, computers speak binary (0s and 1s), and hex is the translator between the two. Hex uses 16 symbols: 0-9 for zero through nine, and A-F for ten through fifteen.

Why 16? Because one hex digit = exactly 4 bits. This makes hex incredibly efficient: the 8-bit binary 11111111 becomes just FF in hex (255 in decimal). This is why memory addresses, color codes, and MAC addresses all use hexadecimal—it's compact and directly maps to binary.

Expert Tip: Hex Color Codes in Web Design

Web designers, this is crucial: Every hex color code follows the format #RRGGBB, where RR, GG, and BB are hex values (00-FF) for Red, Green, and Blue. For example, #FF5733 means Red=255, Green=87, Blue=51 (a vibrant orange). Pro tip: Shorthand notation like #FFF expands to #FFFFFF (white). Use our calculator to convert RGB decimal values to hex for your CSS!

Common Mistake: Confusing Letters and Numbers

Beginners often forget that A-F are hex digits, not variables. The hex number CAFE is a valid number (51,966 in decimal), not a word! Another mistake: writing hex without the 0x prefix in code can cause errors. In JavaScript, let x = FF; will fail, but let x = 0xFF; works. Also, hex is case-insensitive: ff, FF, and Ff are all the same (255).

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Reviewed by Mike Liu, Senior Developer

"Hexadecimal is fundamental for low-level programming and web development. This tool handles both directions (dec↔hex) flawlessly, which is essential for debugging memory dumps, setting color codes, or working with byte-level data. The real-time conversion makes it perfect for learning."

Last Updated: November 26, 2025

Frequently Asked Questions

What is hexadecimal (hex)?

Hexadecimal (hex) is a base-16 number system that uses 16 symbols: 0-9 for values 0-9, and A-F for values 10-15. It's widely used in computing because it's more compact than binary—one hex digit represents exactly 4 bits (binary digits). For example, the decimal number 255 is FF in hex, which equals 11111111 in binary.

How do I convert decimal to hexadecimal?

To convert decimal to hex manually: 1) Divide the decimal number by 16. 2) Record the remainder (0-15, where 10-15 are A-F). 3) Repeat with the quotient until it reaches 0. 4) Read the remainders from bottom to top. Example: 255 ÷ 16 = 15 remainder 15 (F), then 15 ÷ 16 = 0 remainder 15 (F). Result: FF. Our calculator does this instantly for any number.

Why do programmers use hexadecimal?

Programmers use hex because: 1) It's compact—two hex digits represent one byte (8 bits). 2) It's easier to read than binary (FF vs. 11111111). 3) Memory addresses are displayed in hex. 4) Color codes in web design use hex (#FF5733). 5) Debugging low-level code requires hex understanding. Hex is the perfect middle ground between human readability and computer binary.

What's the difference between 0x, #, and plain hex?

These are just different notations: '0x' prefix is used in programming (C, JavaScript, Python) to indicate hex literals—e.g., 0xFF = 255. '#' prefix is used in CSS/HTML for color codes—e.g., #FF0000 = red. Plain hex (no prefix) is the raw hexadecimal value. They all represent the same hex number; the prefix just tells the computer or browser how to interpret it. Our calculator accepts hex input with or without prefixes.

How do hex color codes work?

Hex color codes use 6 digits (3 pairs) to represent RGB values: #RRGGBB. Each pair is a hex value from 00 to FF (0-255 in decimal). For example, #FF5733 means Red=255 (FF), Green=87 (57), Blue=51 (33). Pure red is #FF0000, pure green is #00FF00, pure blue is #0000FF, white is #FFFFFF (all max), and black is #000000 (all zero). Use our calculator to convert decimal RGB values to hex for CSS.

References & Further Reading