Cat Calorie Calculator
A neutered adult cat needs 1.2 times its resting requirement — barely more than doing nothing.
The formula
RER = 70 * kg^0.75 ; daily need = factor * RER
Why the three-quarter power
Energy use does not scale with body mass but with roughly its three-quarter power — Kleiber's law, which holds across animals from mice to elephants. The practical consequence is that a 40 kg dog needs about three times the food of a 10 kg one, not four times. Feeding by simple proportion systematically overfeeds large animals and underfeeds small ones.
The multiplier does more work than the weight
An entire working dog and a neutered house dog of identical weight differ by nearly a factor of two in what they need. Neutering alone drops the requirement by about a fifth, which is most of the reason animals gain weight after the operation while being fed exactly as before.
A starting point, then weigh
These formulas describe an average animal, and individuals vary by a good 20 % either side. The right procedure is to start here, then weigh the animal every couple of weeks and adjust. The scales are the measurement; this is only the opening guess.
This does not replace a veterinarian
Every figure on this page comes from a published reference range, and a range is what it stays. The right dose for an individual animal depends on its kidney and liver function, on what else it is taking, on whether it is pregnant or very young or very old, and on what is actually wrong with it — none of which arithmetic can see. Use this to understand the scale of a dose or an exposure, and to have a better conversation with your vet. Do not use it to start, stop or change a medication.
If you believe your animal has swallowed something toxic, do not wait to see whether signs develop. Contact your veterinarian or an animal poison line immediately — in most poisonings the treatment that works is the one given early.