How can I calculate the total number of words I can squeeze in?
—Tales Boalim, Moura Informática
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The answer depends on which type of Electronic Product Code (EPC) tag you are using. There are tags with no user memory at all, and others with 8 kilobytes of memory. To find out how many words you could store in an 8-kilobyte tag, I reached out to Ken Traub, the principal at Ken Traub Consulting. He has been involved with the development of EPC software standards and is knowledgeable about all things EPC.
Ken says that the best way to store information in an EPC tag’s user memory would be to use plain-text characters. As for the number of words that can be stored, he says: “The largest available EPC RFID tags have a user memory of 8,192 bytes (65,536 bits). If you figure an English-language word averages five letters, plus a space between each, then in 65,536 bits you could store about 1,365 words, if you store each character as 8 bits (65,536 bits divided by 8 bits/character divided by 6 characters/word = 1,365 words). You could restrict yourself to 7-bit ASCII characters and squeeze in 1,560 words, or you could restrict yourself to all uppercase letters, using only 6 bits per character, and squeeze in 1,820 words.”
—Mark Roberti, Founder and Editor, RFID Journal