Hex Byte Swap
Swap the byte order of a hex value — the informal name developers often use for reversing bytes between big-endian and little-endian.
Built by
Swapnil SanghviFull-Stack Web Developer & WordPress Developer
Swapnil Sanghvi is a full-stack web and WordPress developer, UI designer, and full-time freelancer who builds and maintains Hex Calculator.
Further reading: Endianness — Wikipedia
How Byte Swapping Works
Split the value into 2-digit byte pairs, then write those pairs back in the opposite order. Each byte's own value is untouched — only the sequence they appear in flips, exactly what a BSWAP-style CPU instruction does in hardware.
Where Byte Swapping Actually Comes Up
Verifying a bswap()-Style Function's Output
Checking that a language's built-in byte-swap function (like C's __builtin_bswap32 or Python's int.from_bytes with byteorder swapped) produces the value you expect.
confirm bswap32(0x12345678) == 0x78563412
Manually Working Through a Networking Bug
When debugging a byte-order mismatch between a sender and receiver, swapping a suspect value by hand and checking if it now looks correct is a quick diagnostic step.
swap the value, see if it makes sense now
Converting Between Codebases With Different Conventions
When porting code between systems with different native byte orders, swapping known constant values confirms they'll be interpreted the same way on both sides.
port a magic number between platforms
Why Use This Calculator Instead of Doing It by Hand
- Handles the byte-splitting and swap for values of any length
- Automatically pads odd-length input to a whole number of bytes first
- Runs entirely in your browser — nothing you type gets sent anywhere
- Avoids the easy hand-reversal mistake of swapping nibbles instead of whole bytes
Limitations
- Swaps whole bytes only — an odd number of hex digits gets a leading zero nibble added first, which can shift byte boundaries if that wasn't intended.
- This is a pure byte-order swap, not a bit-order reversal — the bits inside each byte stay in the same order.
Frequently Asked Questions
Is "byte swap" a formal term?
It's the informal name most developers use in conversation and code comments for reversing byte order — some languages even name their built-in function for this bswap or __builtin_bswap32, matching the everyday term.
Does "byte swap" mean the same thing as endian conversion?
Yes — swapping bytes and converting between big-endian and little-endian describe the identical operation, just with different names depending on the context you're working in.
Is there a dedicated CPU instruction for byte swapping?
Yes — most modern processors (x86's BSWAP, ARM's REV) have a single instruction that reverses a register's byte order, since it's common enough in networking and file-format code to warrant hardware support.
What happens with an odd number of hex digits?
A leading zero nibble is added first, since a byte needs exactly two hex digits.