Pet Food Calculator

Feeding guidelines printed on pet food bags are averages built around an average animal, and they systematically overfeed a large share of pets. The more defensible approach is the one veterinary nutritionists use: calculate resting energy requirement from metabolic body weight, then apply a multiplier for life stage, neuter status and activity. Resting energy is seventy times body weight in kilograms raised to the power of 0.75.

That fractional exponent is the part worth understanding. Energy needs scale with metabolic body weight rather than body weight itself, so a dog twice as heavy needs roughly 1.7 times the calories, not twice as many. Feeding proportionally by weight consistently overfeeds large animals and underfeeds small ones, which is one reason toy breeds and giant breeds both need portions that look counterintuitive.

Neutering has a substantial and frequently overlooked effect, reducing energy requirements by around twenty to thirty percent. Because portions are rarely adjusted afterwards, the period following a neuter is one of the most common points at which pets begin gaining weight. Cats are affected particularly strongly, as an indoor neutered cat has a notably low multiplier.

Treats are where the arithmetic usually breaks down. The standard guideline is that treats should stay at or below ten percent of daily calories, with the rest coming from complete nutrition. Because treats are easy to give and rarely counted, they routinely push intake well past target. Given that a large fraction of dogs and cats in developed countries are overweight, and that excess weight measurably shortens lifespan and worsens joint disease, counting them is worth the effort.