Endianness / Byte-Order Swapper — Big-Endian ⇄ Little-Endian Hex Converter

Big-endian and little-endian, side by side

Every multi-byte number has to be laid out as an ordered sequence of bytes before it is stored in memory, written to a file or sent over a network. Endianness is simply the rule that decides that order. Big-endian stores the most-significant byte first — the same direction we write numbers, so 0x12345678 is laid out 12 34 56 78. Little-endian stores the least-significant byte first, so the very same value becomes 78 56 34 12. This tool takes one value, splits it into bytes for the width you pick, and shows both orderings together: the byte boxes, both hex forms, and the two unsigned decimal numbers you would read back. Everything runs in your browser — nothing is uploaded.

How the swap is computed

The algorithm is deliberately simple, which is exactly why byte order is so easy to get wrong by hand. First the value is padded to the full width in hexadecimal — two hex digits per byte, so a 32-bit value is always eight hex digits. Those hex digits are then sliced into bytes of two characters each. To swap endianness, you reverse the byte list and join it back together; nothing else changes. Because reversing a list twice restores the original order, byte-swapping is its own inverse — swap 0x12345678 to 0x78563412 and swap again and you are back where you started. Reading each ordering back as an unsigned integer gives two different decimal numbers, which is why a swapped value looks unrelated even though it is built from the identical four bytes. For 64-bit widths the tool uses BigInt so values up to 0xFFFFFFFFFFFFFFFF stay exact.

Where you meet each byte order

Little-endian is what most hardware uses internally: x86, x86-64 and the common ARM configurations all store integers least-significant-byte-first, as do file formats such as BMP, WAV, and ZIP. Big-endian — historically called the Motorola order — survives as network byte order in TCP/IP, so a TCP port or an IPv4 address travels most-significant-byte-first, and it is used by PNG, JPEG, and TIFF files tagged MM. The C functions htons/htonl (host-to-network) and ntohs/ntohl (network-to-host) are exactly this swap on little-endian machines, and CPUs expose a dedicated BSWAP instruction to do it in one step.

Quick reference

About the Endianness / Byte-Order Swapper — Big-Endian ⇄ Little-Endian Hex Converter

Working on everyday tasks? The Endianness / Byte-Order Swapper — Big-Endian ⇄ Little-Endian Hex Converter is a free browser tool that gives you the answer in seconds. Swap a value between big-endian and little-endian byte order. Enter a hex (with or without 0x) or decimal value, choose 16, 32 or 64-bit width, and see the byte layout, both hex forms and both unsigned decimal interpretations — live, in your browser, with click-to-copy.

How it works

Enter a number and choose your units — the converted value shows instantly. Everything runs locally, so nothing you type leaves your device. Double-check the direction of the conversion and you are set.

Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.

Frequently Asked Questions

Common Use Cases