Hex to Decimal Converter

What the hex digits mean

Hexadecimal uses sixteen symbols. The digits 0–9 keep their usual values, then the letters A–F continue the count: A = 10, B = 11, C = 12, D = 13, E = 14 and F = 15. Case does not matter, so ff and FF are the same number. Many hex values carry a 0x prefix or a trailing h to mark them as base 16; you can ignore those markers when converting.

The powers-of-16 method

Each hex position is worth a power of sixteen: 1, 16, 256, 4096 reading right to left. Multiply each digit's value by its column weight and add everything up. Take 2F:

2 F
F = 15, 2 = 2
2×16 + 15×1 = 32 + 15 = 47

So 2F equals 47. For the classic byte maximum FF: 15×16 + 15 = 240 + 15 = 255. A two-digit hex number always covers exactly one byte, from 00 (0) to FF (255), which is why hex is so natural for describing bytes.

The doubling-style shortcut

For longer hex strings, process left to right: start at 0, then for each digit multiply the running total by 16 and add the digit's value. For 1A3: 0×16+1 = 1, 1×16+10 = 26, 26×16+3 = 419. This avoids juggling large powers and is exactly how the converter evaluates the string with BigInt for unlimited length.

Reference table

Two hex digits = one byte (0–255), four = two bytes (0–65535), eight = a 32-bit word (up to 4,294,967,295). Recognising these boundaries helps you tell at a glance how wide a value is.

Common real-world hex

• Color codes like #1E90FF split into three bytes: red 30, green 144, blue 255.
• Memory addresses in debuggers and stack traces, e.g. 0x7FFE0000.
• Unicode code points such as U+1F600 (the 😀 emoji = decimal 128512).
• HTTP status hex dumps, exit codes and error registers.