Human's impact on earth through global warming is more or less an accepted fact. Ocean freight is estimated to contribute 4–5% of global carbon emissions and manufacturing companies can aid in reducing this amount. Many companies that ship goods through full container loads do not have the capabilities to ensure the containers they are using minimizes their carbon footprint. One of the reasons is the choice of non-ideal container sizes for their shipments. This paper provides a mathematical model to minimize companies' shipping carbon footprints by selecting the ideal container sizes appropriate for their shipment volumes. Using data from a selected real-world business case in the manufacturing industry, we show that our model can provide a 13.4% reduction in carbon footprint. We believe that our model is generic for ocean shipment and can be easily adoptable by other manufacturing companies, to be more environmentally sustainable by selecting the appropriate container sizes and reduce the carbon footprint of their ocean freight.