Reverse Hex Bytes
Reverse the byte order of a hex value — a generic byte-order flip, whatever you happen to call the specific direction.
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 Reversing Hex Bytes 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.
Where Byte Reversal Actually Comes Up
Quickly Flipping a Value Without Naming a Direction
When you just need the byte order flipped and don't need to think in terms of "which is little-endian, which is big-endian" for the specific value you're working with.
any byte sequence -> reversed byte sequence
Verifying a Byte-Order Bug
If a decoded number looks wrong in a suspiciously specific way (digits present but in the wrong grouping), reversing the bytes and checking if that produces a sensible value confirms an endianness mismatch.
garbled value -> reversed -> makes sense
Working With Data From an Unfamiliar Source Format
When you're not sure yet whether a value is stored big-endian or little-endian, reversing it and comparing both readings against what you expect helps you figure out which one applies.
compare both byte orders against expected value
Why Use This Calculator Instead of Doing It by Hand
- Handles the byte-splitting and reversal 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
- Reverses 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 reversal, not a bit-order reversal — the bits inside each byte stay in the same order.
Frequently Asked Questions
What exactly gets reversed — bytes or individual digits?
Whole bytes (2-digit hex pairs), not individual hex digits or bits. 0x123456 reverses to 0x563412 (byte order 12,34,56 becomes 56,34,12), not 0x654321 (which would be reversing every single digit).
Is "reverse hex bytes" the same as endian conversion?
Yes — reversing byte order is exactly what converting between big-endian and little-endian means. This page is a generic version of the same operation as the Little/Big Endian Converters.
What happens with an odd number of hex digits?
A leading zero nibble is added first, since a byte needs exactly two hex digits — this can shift which digits end up paired into which byte, so double-check the padding matches what you intended.
Does reversing twice return the original value?
Yes — reversing byte order is its own inverse, so running a value through this twice always gives back the original value.