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Cat Calorie Needs

Calculate your cat's maintenance calories from weight and activity.

How it is calculated

The tool computes the resting energy requirement from body weight and then scales it by a life-stage factor: RER = 70 × weight0.75 and MER = RER × factor. Weight is in kilograms; both results are kilocalories per day, rounded to whole numbers. The factor is not free-form: only 1.0 (weight loss), 1.2 (neutered adult), 1.4 (intact adult), 1.6 (active) and 2.5 (kitten) are accepted, and any other value, such as 1.3, shows no result. Weights of zero or below, or above 30 kg, also show no result. The output is a population-level estimate; a real cat's needs vary with breed, body condition and health, so adjust against body weight over a few weeks.

Worked example

A neutered adult cat weighs 4.5 kg. Raised to the power 0.75 this is about 3.09, so RER = 70 × 3.09 = 216 kcal per day at rest. The neutered-adult factor is 1.2, so MER = 216 × 1.2 = 260 kcal per day, the maintenance target the tool shows as the main figure. Choosing factor 1.0 for the same cat gives 216 kcal, which is why the factor matters as much as the weight.

Try this example →

Common mistakes

  • Entering weight in pounds. The formula expects kilograms, so a 10 lb cat is about 4.5, not 10.
  • Feeding the resting figure (RER) as the daily target. The main result is MER, the resting energy already multiplied by the factor.
  • Picking the intact-adult factor (1.4) for a neutered cat, which overstates needs by about 17 % (1.4 against 1.2) and is an easy route to weight gain.
  • Looking for a factor between the options. Only the five listed values are accepted, so 1.3 or 0.8 gives no result; choose the closest life stage instead.
  • Ignoring treats and prescription diet, which count towards the total, so the bowl portion should be smaller than the full figure.

Sources

About this calculator

A cat's daily energy needs start from Resting Energy Requirement (RER), typically calculated as 70 × (body weight in kg)^0.75, which estimates the calories needed just to maintain basic body functions at rest. That RER is then multiplied by a life-stage or activity factor — commonly around 1.2 for an average indoor neutered adult cat, 1.4 for an intact adult, 1.6 for an active cat, 2.5 for a kitten in growth, and lower (around 1.0) for a cat that needs to lose weight — to get the actual daily maintenance calories.

Veterinarians and pet-food formulators use this RER-times-factor method as the standard way to set feeding guidelines, since a flat "calories per pound" rule ignores how disproportionately energy needs scale with body size (the ^0.75 exponent reflects that larger animals have relatively lower metabolic rates per kilogram than smaller ones). Owners managing an overweight or underweight cat, or transitioning a kitten to adult food, use it to set a realistic daily target rather than just following the bag's generic feeding chart.

Your cat's weight gives its resting energy, which is multiplied by one of five fixed life-stage and activity factors (1.0, 1.2, 1.4, 1.6 or 2.5) to estimate its daily calories.

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