The plastic footprint is defined as a science-based tool for quantifying the amount of plastic (in kg) one contributes to the world’s plastic waste (from plastic wraps to anything containing plastics, such as clothes). Making consumers aware of their total plastic footprint and of how it is divided among their various daily life activities can promote concrete eco-sustainable actions aimed at reducing it and consequently plastic consumption. To this aim, we developed a free online plastic footprint calculator for making users aware of how much plastic they introduce into the environment through individual consumption, from food to clothing or leisure. In this tool, we also considered the consumption of plastics during mountain activities as it leads to the production of specific plastic waste. We tested the beta version of this tool on a small sample of users, including students, living in the mountains. Our results show that the sector with the greatest impact is food consumption (72.8%, mainly due to plastic drink bottles), followed by mountain activities (17.4%), a sector that was investigated in more detail (i.e., with more questions) than food consumption. Considering only mountain activities, synthetic fleeces are the most widely used and incorrectly managed items (34.7%), followed by shoes for mountain running or hiking (20.8%). We hope this tool will contribute to more aware use and management of plastic items during mountain activities and daily life and help reduce the distribution of plastics into the environment.