Introduction

There are instances when you might acquire an item for sale that lacks a barcode, a scenario increasingly common with local or specialized products. To integrate such items into Passport, creating a custom UPC is essential. A UPC ensures each item's unique identification, facilitating efficient inventory management and sales tracking. This guide details how to generate a custom UPC, focusing on the critical last digit – the check digit – which is pivotal for the barcode's validity.

UPC Check Digit Calculator

Creating a Custom UPC 

A UPC barcode is integral for product identification, where the last digit, known as the check digit, plays a crucial role in validating the barcode's authenticity. This digit helps in mitigating human transcription errors during the barcode scanning process.

Check Digit Calculation

1. Identify digits placed in odd positions within the UPC (excluding the last digit). Sum these digits and multiply the total by three.
2. Sum the digits located in even positions (excluding the last digit). Add this sum to the total obtained from step 1.
3. Divide the resulting sum from step 2 by 10. Note the remainder.
4. If the remainder is not zero, subtract it from 10. The result is your check digit.

Example

1. Consider the barcode ‘810012110099’. Following the calculation steps:
   1. Odd positions sum: 8 + 0 + 1 + 1 + 0 + 9 = 19 | 19 x 3 = 57.
   2. Even positions sum: 1 + 0 + 2 + 1 + 0 = 4 | 57 + 4 = 61.
   3. Division by 10 gives a remainder of 1.
   4. The check digit is 10 - 1 = 9.
      
2. Thus, the check digit for ‘810012110099’ is ‘9’, completing the custom UPC as ‘8100121100999’.