How Despendo calculates your days of food
Why 100 kg of sugar is not months of food. How Despendo counts your days of autonomy: what adds up, what does not and the cap for each group.
The simplest way to know how long your reserves last is to add up all the calories you have stored and divide them by what your family eats each day. It is a good first approximation, and it has one problem: it can be fooled without anyone meaning to.
The sack-of-sugar problem
Picture a person who needs about 2,000 kcal a day. They have 10 kg of rice, 3 kg of beans, 2 liters of cooking oil and 25 kg of sugar. Adding up calories alone gives 82 days. But sugar supplies more than half of those calories, and nobody can live on sugar for three months.
That is why Despendo does not count calories alone. It works out how many days you could eat reasonably with what you have. In that same example the result is 33 days, and the app shows you both numbers so you can see the difference.
What counts and what does not
Only food groups count. Water (which has its own days calculation), Personal hygiene, Cleaning, First aid & medicine and Pets never add up, even if you entered calories for them. Counting the dog's food to feed your children would not help anyone.
The cap for each group
Each food group can cover, at most, a share of what you need each day. If you store more than fits in that share, the excess does not count as extra days.
| Group | Can cover at most |
|---|---|
| Grains | 70% |
| Proteins | 30% |
| Legumes | 25% |
| Dairy | 25% |
| Fruits & vegetables | 25% |
| Fats & oils | 20% |
| Baby | 15% |
| Other | 15% |
| Sugars & sweeteners | 10% |
| Beverages | 10% |
| Condiments & sauces | 5% |
| Ready meals | 100% |
Ready meals (instant soups, rations, bars) are the only ones with no cap, because they are already complete meals.
Where those numbers come from
They are not pulled out of thin air. The World Health Organization recommends that free sugars stay below 10% of daily energy and that total fat stay under 30%. That is why sugar is capped at 10% and oil at 20%, which leaves room for the fat already in meat, dairy and grains.
For the other groups we follow the idea behind the classic long-term storage lists, like the ones explained by The Church of Jesus Christ of Latter-day Saints: wheat, rice, pasta, oats and beans as the base. In the most repeated versions of those lists, per adult per year you see roughly 300 to 400 pounds of grains against about 60 of sugar and about 20 of oil. Despendo turns that proportion into caps per group.
How the math works
Despendo looks for the largest number of days D for which this holds: adding up, per group, what you have stored but never beyond the cap times your daily need times D, the total is enough for those D days. If everything is balanced, the result matches the plain calorie count. If you have far too much of a single group, the result goes down and shows you why.
An example of a balanced pantry: 20 kg of rice, 8 kg of beans, 10 kg of meat and fish, 3 L of oil, 3 kg of sugar and 3 kg of powdered milk for one person give 82 days by calories and also 82 days in Despendo, because no group goes over its cap.
What this number is not
It is a planning estimate, not medical advice. If someone in your home has special needs, adjust what you store with their doctor. And remember the calculation is only as good as the data you enter: a product without calories adds nothing, and one without a category counts as "Other", which has a low cap.
How to improve it at home
The result goes up when your pantry looks like a real diet: more grains and legumes, some protein, a moderate amount of oil and, if you can, dehydrated or canned fruit and vegetables. To split things better, see how much to keep of each in how much food to store per person, and to make each product land in its group, check how shelves and categories work.
Sources and further reading
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