0.4 kilograms is a unit of mass in the metric system, equivalent to 400 grams. It is commonly used to measure the weight of various objects, such as food items, small packages, or personal belongings. For example, a standard loaf of bread typically weighs around 0.4 kilograms. In everyday terms, 0.4 kilograms is slightly less than a liter of water, which weighs about 1 kilogram. This weight can also be compared to common items like a medium-sized apple or a small bag of flour. Understanding this measurement can help in cooking, shopping, and other daily activities.