Other items may be needed by people with special needs so plan accordingly. The amount of an item you needs depends on how long of a period of time, how many people, their age and gender, and what level of activity and stress they will be subjected to. Most female adults will consume less than a male adult but individual difference do exist. In addition, anybody physically active will require additional portions. If your family is working on the garden you'll need bigger meals than if they were sitting around listening to the radio.
Stress can also increase food needs.
One thing to be on guard for is the modern tendency to eat more food than necessary during times of stress. Drinking water should not be rationed. Children, of course, need less food than adults. Teenagers and young adults can need, and will consume, as much as 40-50 percent more than adults. In April or May we will provide a supply calculator at this site.