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Hex to Decimal Converter

Translate hexadecimal into decimal, binary and octal instantly.

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Frequently asked questions

Why is hexadecimal used so widely in computing?

Because one hex digit maps exactly to four bits, so a byte is always two hex digits. That makes hex a compact, lossless shorthand for binary — far easier to read than eight ones and zeros, and much better aligned than decimal.

What do the letters A to F mean?

They are the digits for ten through fifteen, since base-16 needs sixteen symbols and decimal only supplies ten. So A is 10, F is 15, and FF is 255.

What do the 0x and # prefixes mean?

Both just signal that what follows is hexadecimal. 0x is the convention in most programming languages, while # is used for colours in CSS and design tools. Neither changes the value.

Pro tips

  • Read a hex value as pairs of digits when it represents bytes; the pairing is the whole reason hex is used there.
  • Use the bitwise panel to check a permission or flag value rather than reasoning about it in decimal, where the bit pattern is invisible.
  • Watch for the leading-zero octal trap when copying a permission value into source code as a number.
  • Remember that shifting left by one doubles a value and shifting right halves it, which is often a faster sanity check than converting.
  • Values beyond 2^53 stay exact here, so large identifiers and 64-bit masks convert without the silent rounding a floating-point calculator introduces.

About Number Base Converter

All four bases update together, and the bitwise side runs AND, OR, XOR, NOT and shifts across two values. BigInt underneath means numbers past 2^53 stay exact instead of quietly rounding.

Convert a hexadecimal value to decimal, binary and octal simultaneously, and run AND/OR/XOR and bit-shift operations. BigInt keeps large numbers exact, and everything runs locally.

Convert any integer between binary, octal, decimal and hexadecimal all at once, and run AND, OR, XOR, NOT and bit-shift operations on two values. It is an essential helper for low-level programming, embedded work, networking masks and debugging bit flags.

All four bases stay in sync as you type, so one value can be read in each without converting twice. The bitwise panel earns its place when you are working with permission bits, feature flags or network masks.

Hexadecimal dominates low-level work for one structural reason: one hex digit is exactly four bits, so a byte is always two hex digits and the mapping never needs arithmetic. That clean alignment is why colours, byte dumps, memory addresses and hashes are all written in hex rather than decimal, where no digit corresponds to a fixed number of bits.

Octal survives in one place worth knowing. Unix file permissions group nine permission bits into three digits of three bits each — read, write, execute for owner, group and others — which is why chmod 644 and chmod 755 look arbitrary until you see them as binary. A related trap: in C, Java and several other languages a leading zero marks an octal literal, so writing 0644 as an integer does not give you six hundred and forty-four.

Common use cases

  • Converting a hex colour channel to its 0-255 decimal value
  • Reading a memory address or error code from a crash dump
  • Decoding a hex byte value while inspecting a binary file format
How it comparesA programmer calculator such as the one in Windows or macOS covers the same ground and shows one base at a time. Seeing all four simultaneously is the difference when you are trying to spot which bit changed between two values.