Work out cat food quantity instantly with clear inputs, formula shown and shareable results.
The same allometric rule applies to cats: RER is 70 times weight to the power 0.75, scaled by a life-stage factor and converted to grams using the food's energy density. Neutering cuts a cat's energy needs by roughly a fifth while appetite stays the same, which is why post-neutering weight gain is so common.
Resting energy
RER kcal = 70 x (body weight kg) ^ 0.75
Daily food
grams = RER x life stage factor x 100 / kcal per 100 g
RER kcal = 70 x (body weight kg) ^ 0.75. The same allometric rule applies to cats: RER is 70 times weight to the power 0.75, scaled by a life-stage factor and converted to grams using the food's energy density.
Neutering cuts a cat's energy needs by roughly a fifth while appetite stays the same, which is why post-neutering weight gain is so common.
Enter cat's weight, life stage, food energy density. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.