Cat Food Calculator
Calculate cat food easily with our free tool. Get practical results, tips, and comparisons for everyday decisions. Free to use with no signup required.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
RER = 70 × (Weight kg)^0.75 | Daily Calories = RER × Activity Factor
Resting Energy Requirement (RER) is the standard veterinary formula for calories needed at complete rest, based on the allometric scaling law (metabolic rate scales with body weight to the 0.75 power, not linearly). Daily Energy Requirement (DER) multiplies RER by an activity factor: 1.2 for indoor/neutered adults, 1.4 for moderately active cats, and 1.6-2.0 for active cats, pregnant/nursing cats, or growing kittens. Divide DER by the food's calories-per-gram (on the label or from the manufacturer) to get the daily feeding amount in grams.
Worked Examples
Example 1: 4.5 kg indoor adult cat
Problem:A 4.5 kg spayed indoor cat eats dry food rated 3.5 kcal per gram. How much should she eat daily?
Solution:RER = 70 × 4.5^0.75 = 70 × 3.10 = 217 kcal\nActivity factor (indoor/neutered) = 1.2\nDER = 217 × 1.2 = 260 kcal/day\nDaily food = 260 / 3.5 = 74 g/day
Result:74 g/day (~2.6 oz), split into 2-3 meals of ~25g each
Example 2: Growing 3 kg kitten
Problem:A 3 kg kitten (still growing) eats kitten food rated 4.0 kcal per gram. How much daily food is needed?
Solution:RER = 70 × 3^0.75 = 70 × 2.28 = 160 kcal\nActivity factor for growing kittens = 2.0 (double adult maintenance)\nDER = 160 × 2.0 = 320 kcal/day\nDaily food = 320 / 4.0 = 80 g/day
Result:80 g/day, split into 3-4 smaller meals to support rapid growth
Frequently Asked Questions
How much food should I plan per person for a party or event?
As a general planning rule, budget about 1 to 1.5 pounds of food per adult for a full meal (less for an appetizer-only gathering, more if teens or heavy eaters are attending), and plan roughly 1.5 to 2 drinks per person per hour for events serving alcohol. For finger-food or cocktail-style events, 6 to 8 appetizer pieces per guest over a 2-hour window is typical. Always round up rather than down for food quantities — running slightly short is far more noticeable to guests than having modest leftovers, and dishes with mixed dietary needs (vegetarian, gluten-free) should be planned as a percentage of the guest list rather than an afterthought.
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy