Hex to Decimal Converter — Instant Hexadecimal to Base-10

Converting hex to decimal, explained

Hexadecimal (base 16) is the most common number system after decimal in programming. A hexadecimal number uses the digits 0-9 and the letters A-F, where A represents 10, B is 11, and so on up to F which represents 15. Converting hex to decimal means rewriting the number in the familiar base-10 system that humans count with. This hex to decimal converter does the conversion instantly in your browser with arbitrary precision — it can handle 256-bit cryptographic values and 512-bit hashes as easily as a two-digit RGB channel.

The conversion formula

To convert a hex number to decimal by hand, multiply each digit by the power of 16 matching its position (counting from the right, starting at 0), then sum the results. For example, to convert 2A3 to decimal:

2 × 16² + A × 16¹ + 3 × 16⁰
= 2 × 256 + 10 × 16 + 3 × 1
= 512 + 160 + 3
= 675

So hex 2A3 equals decimal 675. For large numbers, doing this by hand is tedious and error-prone; the tool above does it instantly and keeps full precision even for 256-bit inputs.

How to use this hex to decimal converter

1. Type or paste a hexadecimal number into the hex field. Upper or lowercase is fine — FF, ff, and Ff all convert to decimal 255.
2. The decimal field updates live with the base-10 equivalent. Binary and octal values also appear for reference.
3. A 0x prefix is optional; paste 0x1A or 1A, both work.
4. Invalid characters (anything outside 0-9, A-F) surface an inline error so you know exactly what went wrong.

Examples

Hex     Decimal
FF      255            # one byte
100     256
FFFF    65535          # uint16 max
DEADBEEF  3735928559   # famous debug magic number
0x1A    26             # prefix is fine
ABCDEF0123456789  12379813812177893257  # big, handled

The tool uses JavaScript BigInt internally, so values past Number.MAX_SAFE_INTEGER (2^53 - 1) stay exact. This matters for cryptographic keys, SHA-256 digests, and any hex-encoded 64-bit or wider value.

Why hex exists and why developers use it

Computers process bits. Humans find long bit strings unreadable (10101010), so hex emerged as a compact alternative: every group of 4 bits maps to exactly one hex digit, and every byte (8 bits) maps to exactly two hex digits. That makes hex the natural notation for:

• Memory addresses. A 64-bit address shown in hex is 16 characters (0x7ffe8c0d1a40); in decimal it would be up to 20 digits with no byte boundary visible.
• Byte values. Every byte is two hex digits, making hex dumps naturally aligned.
• Cryptographic hashes. SHA-256 produces 32 bytes, shown as 64 hex characters.
• RGB colors. CSS uses #RRGGBB where each channel is a byte in hex.
• Register values in debuggers. Assembly, disassembly, and debugger outputs show values in hex by convention.

Converting to decimal is typically needed when you want to compare against a human-written value, plug a number into a formula, or explain a result to a non-engineer.

Common hex to decimal conversions

1     = 1
A     = 10
F     = 15
10    = 16
FF    = 255
100   = 256
1000  = 4096
FFFF  = 65535
10000 = 65536

Privacy

This hex to decimal converter runs entirely in your browser. Numbers are parsed and converted locally via JavaScript BigInt. Nothing is sent to a server, nothing is logged. Safe to paste any value you are working with — memory addresses, private key fragments, hash fingerprints.

Frequently asked questions

Does the 0x prefix matter?

No. The tool strips a leading 0x automatically. Both 0xFF and FF convert to 255.

Is there a limit on the hex value size?

No practical limit. The tool uses JavaScript BigInt, which supports arbitrary-precision integers. Pasting a 1024-character hex value (a 4096-bit number) converts correctly.

How do negative hex numbers work?

Hex itself is unsigned; negative values are represented by their two's complement in a fixed bit width (e.g., 0xFFFFFFFF as a signed 32-bit integer is -1). This tool treats hex input as unsigned. If you need signed interpretation, compute it as value − 2^N where N is your bit width.

Why is A = 10 and F = 15?

Hex needs 16 distinct digits. The digits 0-9 cover the first 10; the next 6 values are assigned the letters A-F by convention because they were the easiest symbols to add to a typewriter and a 6-bit character code in the 1960s.

What is the difference between hex and base64?

Both encode binary data as ASCII text. Hex uses 16 symbols and each byte becomes 2 characters (33% efficiency worse than binary). Base64 uses 64 symbols (A-Z, a-z, 0-9, +, /) and each 3 bytes become 4 characters (75% efficiency). Use hex when human readability and byte alignment matter; use base64 when transport efficiency matters.