📡 RFID Card Number Converter

Convert RFID card numbers between Decimal, HEX and Swapped Endian formats used by access control systems. Bulk upload via CSV or Excel.

  1. Single Converter: Select your input format (Decimal, HEX, HEX Swapped, or Decimal Swapped), enter the card number and click Convert. All four formats are shown instantly.
  2. What is Swapped Endian? Many access control readers (HID, EM4100) store card numbers with byte order reversed. For example, decimal 4274176999 is FEC2C3E7 in HEX, but E7C3C2FE in swapped byte order. Your software may require one or the other.
  3. Bulk Convert: Upload a CSV or Excel file with card numbers in any one column. Use the Download Template button to get a correctly formatted starter file. The tool fills in all missing formats and gives you a downloadable result file.
  4. Which format does my system use? Check your access control software documentation. Most Wiegand-based systems use Decimal. HID systems often display HEX Swapped. If unsure, try both decimal and swapped decimal — one will match what your reader prints on the card.
Single Card Converter
Input Format
Card Number (Decimal)
Invalid input for selected format. Please check your value.
Bulk Converter — CSV / Excel Upload
File Format Requirements
RFID DecimalRFID HEXRFID HEX (Swapped Endian)RFID Decimal (Swapped Endian)
4274176999(auto-filled)(auto-filled)(auto-filled)
1234567890(auto-filled)(auto-filled)(auto-filled)

Your file needs at least one column with values. Accepted columns: RFID Decimal, RFID HEX, RFID HEX (Swapped Endian) or RFID Decimal (Swapped Endian). The tool detects which column has data and fills in the rest. Accepted files: .csv or .xlsx

About This Tool

The RFID Card Number Converter handles one of the most common frustrations in access control system management — card numbers that look completely different depending on which software or reader you're using. The same physical card can appear as four different numbers depending on whether the system displays it in decimal, hexadecimal, or with its bytes in reversed (swapped endian) order.

This happens because RFID cards store a 32-bit (4-byte) number, and different manufacturers read those bytes in different orders. HID ProxCard readers, EM4100 cards and many Wiegand-based systems all have their own conventions. When you're migrating between systems, enrolling cards manually, or troubleshooting why a card isn't being recognised, being able to convert between all four formats instantly saves significant time.

The bulk upload feature accepts CSV or Excel files and fills in all missing format columns, making it practical for provisioning batches of cards or auditing an existing card database. Everything runs in your browser — no card numbers are sent to any server.