Net weight is a term that describes the weight of an item, minus the weight of any container or packaging in which it sits and the weight of any additional items that contribute to its total, or gross, weight. While the term is normally associated with commercially produced and packaged items, such as cereal, apples or detergent, it can also apply to people, live chickens, or any weighable item. The requirement for commercial vendors to measure net weight ensures that consumers can judge for themselves whether they are receiving good value for the money they spend on products.
To calculate an item's net weight, it is necessary to know two measurements: the total weight and the tare weight. The simplest calculation is total weight minus tare weight. Total weight is the mass displacement in pounds or kilograms of the entire item, including its packaging and anything else attached to it. Tare weight is the combined mass displacement of the container, packaging, or other included elements that are not considered the actual product. Subtracting the tare weight from the total weight always yields the net weight.
An example of a product where it is necessary to know net weight is boxed breakfast cereal. When a consumer purchases a box of cereal, simply looking at a large container might lead him to believe he is purchasing more cereal than if he buys a smaller container. If the net cereal weight in both containers is the same, the consumer can then make an informed decision on the value of the cereal purchase price. Generally, if the net differs, the consumer must divide the price by the weight units to determine which product has more value for the money.
If a consumer purchases 11 pounds (about 5 kg) of oranges in a crate, the total weight of the purchase including the crate might be 15 pounds (about 6.8 kg). The consumer should pay only for the 11 pounds (about 5 kg) of oranges in his purchase price, rather than for the tare weight of the crate in which they are packed. Similarly, items that are stored on pallets or plastic sheeting should be weighed separately from those materials to determine their net weight.
A body's net weight is discoverable if a person removes all clothing and accessories before stepping completely naked onto a scale. If modesty precludes such an action, it is also possible to arrive at the same conclusion through a different approach. Measuring the weight of clothing and accessories first provides the tare, or container, weight. Wearing the previously weighed items and then stepping onto the scale will provide the total weight. Subtracting the tare weight from the total weight reveals the net body weight.