Cat Food Calculator

Feeding guides on cat food packaging can be confusing, often giving a wide range that does not account for your cat's exact weight or lifestyle. This calculator uses your cat's weight, activity level and the energy content of their food to give you a general daily portion estimate as a helpful starting point.

How to use the cat food calculator

Enter your cat's weight in kilograms, choose the activity level that best matches their lifestyle, and enter the energy content of their food in kcal per 100g, which you will find on the packaging. The calculator estimates their daily energy needs and converts that into an approximate daily amount of food in grams.

How the calculation works

The calculator starts with a resting energy requirement, using the standard veterinary formula of 70 multiplied by your cat's bodyweight in kilograms raised to the power of 0.75. This resting figure is then multiplied by an activity factor depending on your cat's lifestyle, ranging from 1.0 for a supervised weight loss plan up to 2.5 for a growing kitten. Finally, the daily energy figure is divided by your food's energy content and multiplied by 100 to get a daily amount in grams.

Worked example

For a 4kg neutered cat with normal activity, resting energy requirement works out as 70 × 4^0.75 ≈ 198 kcal. Using the neutered, normal activity multiplier of 1.2, daily energy needs come to around 238 kcal. If their food contains 350 kcal per 100g, that works out as (238 ÷ 350) × 100 ≈ 68g of food per day, typically split across two or more small meals.

Wet food, dry food and mixed feeding

Because wet food contains far more water than dry food, the same weight of wet food provides much less energy. If you feed a mix of wet and dry food, it is worth working out roughly how many calories your cat gets from each, then splitting the daily energy total accordingly, rather than simply halving the total weight of food between the two. Most cats do well grazing on several small meals a day rather than one or two large ones, which better matches their natural feeding pattern.

Common mistakes people make

A common mistake is following the feeding guide on the packaging without adjusting for your cat's actual weight and activity level, since these guides are often based on an average cat. Another mistake is not reviewing portions as your cat ages, gains or loses weight, or moves between an indoor and outdoor lifestyle. It is also easy to overlook treats when totting up daily calories, which can make up a surprisingly large share of a cat's intake given how small their overall energy needs are.

Related calculators

See how your cat's age compares to human years with our cat age calculator. If you have a dog too, our dog food calculator and dog age calculator work the same way. When comparing multipack deals or different pouch sizes, our discount calculator can help you work out the real saving on a per-kilogram basis.