Cat food calculator

This cat food calculator will allow you to calculate how much should you feed your cat, how much it costs per day, and how many calories and carbohydrates are hidden in your cat’s food.

You don’t have to count it manually anymore, this cat food calculator will do all the calculations for you. Under the calculator you will find my tips on how to interpret the calculation results!

How to use the cat food calculator

  • If you want to calculate only the macronutrients in the dry matter of cat food, fill in only the data from the feed label – the first part of the data input.
  • If you want to determine how much should you feed your cat, fill in only the data about your cat and additional information about the food – the second part of the data input. Additionally, manually enter the caloric content of the cat food lower in the results section.
  • If there is no calorific value on the package of the food, and you want to calculate how much should you feed your cat, you must complete both parts of the data input so that the calculator can calculate the caloric value of the food by itself.

#1 Data input: Macronutrients in cat food

Enter the percentages of protein, fat, crude fiber and minerals (crude ash) found on the pet food label under “analytical ingredients”. Based on the entered data, the calculator will calculate the percentage of macronutrients in dry matter (DM) and estimate the caloric content of the feed. If you are analyzing the composition of dry food and there is no information on the moisture content of the food on the packaging, you can enter the value 10 in the “Moisture” field.

#2 Data input: Daily energy requirement for your cat

Enter the weight and cost of one package of the food and some important data about your cat’ condition that will allow the calculator to calculate the amount and cost of food that your cat should eat daily. Determining whether your cat is neutered, non-castrated, active or obese is very important as it allows the calculator to assign a precise factor tailored to your cat.
The calculator is designed for adult cats. Remember that kittens should eat freely during the growth phase.

Cat Food Calculator v2.0
Macronutrients in cat food, daily amount of cat food and the cost of it.

How to interpret the results of calculations

#1 Macronutrients in dry matter

The analytical composition that is stated on the package of cat food usually does not contain information about the carbohydrate content, and the percentage of macronutrients in wet food is given to the wet weight (water + food). Different products have different moisture content. Comparing cat food is only possible when the data is brought down to a common denominator – i.e. the percentage of macronutrients in dry matter (without water).


The optimal protein content in ready-made feeds is 25-45% in the dry matter of the cat food.* Cats are carnivores and are poor in digesting plant nutrients, so avoid feeding foods high in plant proteins.


The optimal fat content in the finished feed is 10-30% in the dry matter of the cat food.* Fats are the primary source of energy and essential fatty acids in a cat’s diet.


Cats do not require carbohydrates in their diets. It is assumed that their amount should not exceed 5% in the dry matter of the cat food.* Carbohydrates are not the optimal source of energy because they are poorly absorbed by the cat’s body. When choosing food for your cat, you should look for products that are low in carbohydrates.

#2 Your cat’s caloric intake and cat food amount

The calculator estimates the caloric content of the cat food based and calculates the energy demand for adult cats. If your cat is obese and needs to lose weight, consult your veterinarian or nutritionist before acting on your own.

Caloric content of the food

This calculator allows you to estimate the caloric content of a pet food based on a method using modified Atwater system adapted to the cat’s diet.* This means that the calculation result may slightly differ from the value given by the manufacturer, e.g. from laboratory tests.

The real calorific value of the food depends primarily on its digestibility. It is influenced by many factors, including the quality of the ingredients used. High-quality feeds have a digestibility of around 85-90%, while economical feeds have a digestibility of around 70-80%. To meet the energy and nutrient requirements, the cat needs to eat much more low-quality food than higher-quality food.

Your cat’s daily energy requirements

Daily Energy Requirement (DER) * is the amount of energy (calories) you need to provide your cat with food each day for your cat to be healthy and to function properly. It depends on the cat’s weight and condition, so it can change with changes occurring in the cat, e.g. weight change, aging or castration.

Remember to weigh your cat from time to time and calculate a new daily requirement if necessary.

There are other popular methods that I have not decided to use in the calculator:
The MER (Maintenance Energy Requirement) method allows you to calculate the minimum amount of food that would allow the cat to survive.
The NRC method (National Research Council) does not take into account losses in food absorption, which is incorrect assumption, because food and its ingredients are not absorbed by the cat’s body in 100%.

How much food should your cat eat and how much does it cost

Feeding your cat an roughly estimated amount of cat food can lead to serious health problems, including overweight and obesity.

That is why it is so important to be able to precisely determine how much of a given food your cat should eat each day. This depends on your cat’s condition and the caloric content of the food you are giving your cat.

Remember that if you change your cat’s food or the composition of this food has changed, it is necessary to recalculate the daily amount of food in the calculator.

#3 BONUS Caloric distribution

For the more inquisitive, I added a module to the calculator that calculates the distribution of energy in food. The calculator, based on the given data of the analytical composition, calculates how much energy comes from protein, how much from fat and how much from carbohydrates. The results are in numerical form, but I will reveal that I am working on a more pleasant representation of the data 😉

Note from the author

I created the calculator to perform quick calculations when making manual calculations is difficult, e.g. when visiting a store. The growing interest and demand among conscious cat guardians meant that I published it on my blog.

The calculator makes it easy the analysis of the composition of the food, but it is worth bearing in mind that the composition of ingriedients and dietary additives are also extremely important when choosing a healthy and balanced cat food. I encourage you to take a look at the detailed composition analyzes in my cat food reviews.

In the beginning, the cat food calculator only had one module for calulating macronutrients in dm. After many trials and errors, I was able to write two new modules. This is not the end though! I plan to develop the calculator and add more and more functionalities to it. If you have any suggestions, questions, or notice an error, feel free to leave a comment under the article 🙂

Calculator changes:

  • 12 August 2020 – Testing: Cat Food Calculator 1.
  • 21 August 2020 – Publication in Polish: Cat Food Calculator 1.0
  • September 13, 2020 – Update in Polish: Minor stylistic fixes
  • December 15, 2020 -Testing: Cat food calculator 2.0
  • February 12, 2021 – Publication in Polish: Cat Food Calculator 2.0
  • March 3, 2021 – Update in Polish: Information about the DER method
  • March 19, 2021 – Publication in English: Cat Food Calculator 2.0

* The calculator is based on information from:
– “Podstawy żywienia psów i kotów”, prof. dr hab n. wet. R Lechowski, lek. wet. B Barszczewska, pod redakcją dr n.wet. M. Ceregrzyn, wyd. Edra Urban & Partner, Wrocław 2019
– Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs, 2020, FEDIAF


What do You think?

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Joanna z Apollo Fluffy Cat

I am Joanna and together with my cat Apollo, I create the Apollo Fluffy Cat blog, where I share my experiences and knowledge about cats and ecology so that you can learn how to become a better and more mindful cat parent! You can found more about me, Apollo and our blog's mission on the "About Us" page.

2 thoughts on “Cat food calculator

  1. Hi Joanna,

    Thank you for this! It seems very helpful!

    My kittens are 6months old. Is the amount needed for them the same as an older cat (I selected the ‘neutered’ option)? I filled out the forms and the recommended amount it suggests is much lower than those on the kitten foods. Trying to decide which kitten food(s) to keep them on.


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