30 cubic refers to the measurement of space or volume, often used in logistics and shipping. In the context of shipping, cubic measurements are important for determining dimensional weight and how much space a package will occupy in a shipping container or vehicle. For example, a box that measures 3 feet by 2 feet by 5 feet has a total volume of 30 cubic feet. Shipping carriers use cubic measurements to optimize their space, ensuring that cargo is packed efficiently and that customers are charged accurately based on both weight and volume.