Plastic waste is an environmental crisis that is becoming increasingly well-documented. The rapid expansion of plastic manufacturing and consumption has led to a harmful cycle of pollution and greenhouse gas emissions due to petroleum-based production and plastic waste disposal. Plastic production and disposal depend on the consumption behavior of people. This study aimed to examine the plastic consumption behavior in Thailand and its impact on climate change at the end-of-life stage. The general information, plastic consumption, and plastic waste management were collected via questionnaires for each product lifetime, including single-use, medium-use, and long-use plastics. Based on 567 questionnaires, the results showed that people consumed single-use plastic, e.g., plastic bag, food container, cutlery, straws, and bottles, at a rate of about nine pieces/household/day or three pieces/cap/day. The medium-use and long-use plastic were 10 pieces/household/month and 50 pieces/household/year, respectively. It should be remarked that population density, education, and number of household members affected plastic consumption behavior, especially for single-use plastic. Regarding the disposal of end-of-life plastics, Thai people, on average, contribute 0.15 kg CO2eq/household/day to climate change. Many households have mismanaged waste by open dumping and open burning. Therefore, practicing proper waste management will help Thailand on the path to carbon neutrality in the future.