NFC UID / Card Number Converter

Enter a UID or card number to instantly view hex, decimal, and reversed byte order results.

NFC UID / Card number

Input format

Output formatting

Byte colors

HEX letter case

HEX separator

Hex · Original

MSB → LSB

—

Hex · Reversed

LSB → MSB

—

Decimal · Original

MSB → LSB

—

Decimal · Reversed

LSB → MSB

—

Bytes—

Bits—

Compare card numbers

Left card number

Waiting

Right card number

Batch conversion

Card numbers (one per line)

Output mode

Results

Why can the same NFC card show different numbers?

Apps and card readers may use hexadecimal (HEX), decimal, or different byte orders. Reversing the byte order moves each pair of HEX digits as a unit: for example, 04 A1 B2 C3 becomes C3 B2 A1 04.

Bytes and bits describe the length of your input, not the card’s capacity. Systems that use other encoding rules may display a different card number.

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