Hex to Decimal Converter

Hexadecimal appears everywhere in development: HTML color codes, memory addresses, byte values in network packets, hash outputs, Unicode codepoints. The hex system exists because it maps cleanly to binary — 2 hex digits = 1 byte — and compresses long binary strings into something humans can actually read. This converter translates between hex and decimal (plus binary and octal) instantly.

What Is Hexadecimal (Base 16)?

Hexadecimal is a base-16 positional numeral system. It uses 16 symbols: 0–9 for values 0–9, and A–F (or a–f) for values 10–15.

The 0x prefix (e.g., 0xFF) is a programming convention indicating a hexadecimal literal. This tool accepts both FF and 0xFF.

How Hex to Decimal Conversion Works

Multiply each hex digit by its positional power of 16 and sum.

Example: 1A3 → decimal

1A3 = 1×16² + 10×16¹ + 3×16⁰
    = 256 + 160 + 3 = 419

Example: FF → decimal

FF = 15×16¹ + 15×16⁰ = 240 + 15 = 255

0xFF is the maximum value of a single byte — which is why you see it constantly in color codes, bitmasks, and byte-level operations.

Why Hex Maps Perfectly to Binary

One hex digit = exactly 4 bits (a nibble). Two hex digits = exactly 1 byte (8 bits). This isn’t coincidence — 16 = 2⁴, so every possible hex digit maps to a unique 4-bit pattern.

0xFF = 1111 1111 (all bits set, 255 decimal)
0x0F = 0000 1111 (low nibble only, 15 decimal)
0xF0 = 1111 0000 (high nibble only, 240 decimal)

This is why developers use hex instead of decimal for bitmasks: value & 0xFF (extract low byte) is immediately readable as a bit operation; value & 255 is not.

Real-World Hex Values You’ll Encounter

HTML/CSS Colors

CSS hex colors are three bytes — red, green, blue:

• #FF0000 = rgb(255, 0, 0) = full red
• #00FF00 = rgb(0, 255, 0) = full green
• #1A1A2E = rgb(26, 26, 46) = dark navy

Shorthand #FFF = #FFFFFF because each digit is doubled.

Memory Addresses (x86-64)

64-bit pointers are written as 16 hex digits: 0x00007FFD4B2A1C30. The 0x prefix signals to readers that this is a hexadecimal memory address, not a decimal number.

Unicode Codepoints

Characters are identified by hex codepoints:

• U+0041 = ‘A’ (decimal 65)
• U+00E9 = ‘é’ (decimal 233)
• U+1F600 = 😀 (decimal 128512)

Status Codes and Flags

HTTP status 404 = 0x194. Error codes in Windows are hexadecimal: 0xC0000005 (access violation), 0x80070057 (invalid parameter).

Converting Decimal to Hex

To convert decimal to hex, repeatedly divide by 16 and record remainders:

419 ÷ 16 = 26 remainder 3   → 3
26 ÷ 16  = 1 remainder 10   → A
1 ÷ 16   = 0 remainder 1    → 1

Read remainders bottom to top: 1A3

Or just use the tool above — the “Decimal → Hex” panel does this instantly.

Frequently Asked Questions

What does 0x mean in front of a number? It’s a programming prefix indicating the following digits are in base 16 (hexadecimal). Originating from C, it’s now used in virtually every programming language. 0xFF = 255 decimal.

Is hex case-sensitive? No. 0xFF and 0XFF and FF and ff all represent the same value. Uppercase is conventional for standalone values; lowercase is common in CSS color codes.

Why are hex numbers often 2, 4, or 8 digits long? Because 2 hex digits = 1 byte, 4 hex digits = 2 bytes (16-bit word), 8 hex digits = 4 bytes (32-bit word). Padding to even digit counts makes the byte boundaries immediately visible.

Privacy

All conversions run entirely in your browser. No data is transmitted to any server.