RFID UID Hex and Decimal Converter
Convert RFID identifiers between hexadecimal, decimal and binary. Preserve leading zero bytes and compare normal and reversed byte order without losing precision.
Calculations run locally. Input values are not submitted to our server.
Result
- Hex bytes
- 04 A1 00 FF
- Decimal, most significant byte first
- 77660415
- Reversed hex bytes
- FF 00 A1 04
- Decimal after byte reversal
- 4278231300
- Binary
- 00000100101000010000000011111111
Worked example
Hex 00 00 00 2A is decimal 42 with a four byte width. Reversing its bytes produces 2A 00 00 00, decimal 704643072.
Method and assumptions
A UID is a byte sequence. Different readers may display those bytes in a different order or convert them to a decimal number. Match both the byte width and the documented reader format. Byte reversal is a display conversion, not a change to the tag. A UID alone does not prove authenticity and does not reveal keys or access permissions.
References
Calculation logic reviewed 17 October 2026. Read our methodology.