The growing concern over global carbon emissions and their impact on climate change necessitates innovative solutions to raise awareness and drive behavioral change. This paper presents CarbonMetric, a mobile application designed to calculate an individual’s carbon footprint from everyday car journeys and provide personalized recommendations to reduce it. The application leverages data on vehicle type, fuel consumption, and journey length to compute emissions and suggests alternative actions to users based on their behavior. CarbonMetric’s current design offers a user-friendly interface that simplifies data input and provides actionable feedback, making it a valuable tool for promoting sustainable practices. The system’s adaptability and intelligent decision-making processes exemplify how mobile technology can support urban environmental strategies and align with smart city initiatives.