250 ml to 400 ml. The standard quantity of box lunch is usually calculated in grams, not milliliters. Different restaurants and suppliers have different standard lunches, but they are usually between 200 grams and 400 grams. Specifically, in a standard box lunch, rice accounts for about half of the volume (or weight), and the other half is various main courses, side dishes and juices. Therefore, if we take a 500ml food container as an example, the actual food quantity of a standard box lunch is about 250ml to 400ml. It should be noted that the types, tastes and cooking methods of the ingredients contained in the box lunch will also affect its actual weight and volume. At the same time, when choosing a box lunch, you should consider whether you need to add other side dishes or staple foods according to your own needs.