Variability in consumer practices and choices is typically not addressed in comparisons of environmental impacts of traditional shopping and e-commerce. Here, we developed an analytical model to quantify the variability in the Carbon footprints of product distribution and purchase of nine products category via two prevalent retail channels in the city of Torino. We found that shopping online most likely decreases the Carbon footprints when substituting traditional shopping, while products purchased through traditional retail often have higher Carbon footprints compared to those purchased via traditional retail. The number of items purchased, and the last-mile travel distance are the dominant contributors to the variability in the Carbon footprints of the two retail channels.