This paper introduces the design and development of a Personalised Carbon Accounting Software (PCAS) aimed at individuals and families to address and mitigate their impact on climate change. Through a detailed analysis of existing carbon accounting tools, it was observed that many lack personalisation and long-term user engagement, which are critical for sustained behaviour change towards reducing carbon footprints. The proposed web-based PCAS emphasises user-friendly features, personalised feedback, and educational resources to enhance user retention and effective engagement. The software development follows a structured methodology employing Python and Django frameworks, ensuring a robust, scalable system. The research underscores the significant role of personalised tools in promoting sustainability and environmental responsibility among individuals, positioning PCAS as a vital tool in the fight against climate change.