Why does the daily ration change a kibble's real cost?

The daily ration is the amount actually served to cover the energy requirement; it, and not the price per kilo, sets how fast the bag empties. The smaller the ration needed, the longer the bag lasts and the lower the cost per day, at equal price per kilo. In depth ### The ration links need and spend The ration bridges the animal's physiology and the wallet: it is worked out by dividing the energy requirement by the food's density. A smaller ration covers the same need with less product, so the bag covers more days. A kibble's real cost is therefore only legible once the ration is known, never from the headline price alone. The effect is quantifiable. At constant need, moving from a food at 350 kcal per 100 g to one at 400 kcal per 100 g cuts the ration by about one eighth, that many days gained on a single bag. Often overlooked: two bags of identical weight do not provide the same number of feeding days if their densities differ, which makes bag weight a misleading indicator of duration. ### Serving the right ration, no more, no less A mis-set ration ruins the calculation in both directions. Too generous, it inflates the cost and favours overweight; too small, it shortchanges the animal. Weighing the ration on a scale rather than measuring by volume makes both budget and nutritional balance more reliable (FEDIAF, labelling and requirements). The stated density is the starting point, body-condition observation the adjustment. Comparison table | Food density | Ration for 600 kcal | Effect on bag duration | |---|---|---| | 300 kcal/100 g | 200 g/day | shortest bag | | 350 kcal/100 g | about 171 g/day | intermediate | | 400 kcal/100 g | 150 g/day | longest bag | | 450 kcal/100 g | about 133 g/day | most durable bag |