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How many calories does my dog or cat need?

on November 19, 2020

Once you’ve determined how many calories are in your pet’s food you then need to work out how many calories they need per day. Calories are units of energy, when our pets eat more calories than they use up the excess is stored as fat and they become overweight, when they have too few calories, they will start to lose weight. Breed, age, environment and lifestyle can all make a difference to the number of calories your pet requires, for example neutering can reduce your pet’s energy requirements by up to 25% so they often require less food after being neutered.


How much energy does your pet use when resting?

To work out your dog or cat’s energy requirements in calories you will firstly need to work out their resting energy requirement or RER. The RER is the amount of energy your pet will use if it did nothing else but just chilled out all day.

For dogs and cats between 2-25Kg the Resting energy requirement (RER) can be calculated approximately by doing this simplified calculation: (30 x your pet’s weight in Kg) + 70

So, for example, if your pet is 10Kg the calculation would be (30 x 10) + 70 = 370. This means that when resting your pet needs 370 Kcals per day. However, our pets don’t rest all day, they also need energy so they can exercise, play, eat, groom, hunt (cats) and for repair, when the body is recovering from illness or injury.

How much energy does your pet need in total?

To work out how many calories your dog or cat needs for normal daily activities, rather than just resting you need to multiply the RER by different factors depending on your dog or cat’s individual needs. For example, there are different factors for different rates of work (for dogs), for pregnant and nursing animals and for weight loss. Additionally, your pet’s genetics play a part in how much energy they require and there are some breeds that are more prone to gaining weight than others.  If your dog or cat needs to lose weight then we have written a blog on how to work out how many calories they need to slim down. (NB all the examples below are for factors relating to non-obese prone breeds)

Neutered adult dog (normal activity) 1.6 x RER = daily amount of calories

Intact adult dog (normal activity) 1.8 x RER = daily amount of calories

Neutered adult cat 1.2 x RER = daily amount of calories

Intact adult cat 1.4 x RER = daily amount of calories

As an example, if we wanted to find out the number of calories a 12Kg neutered adult dog would need, here is the formula:

(30 x 12) + 70 = 430 Kcals RER    then multiply this by 1.6 to get the daily calories required = 688 Kcals.

We’ve worked it out for you!

As you have learned there are multiple factors that impact the overall energy needs of each pet, in addition the calculations above are simplified versions of the more complex equations so we have put all of the complicated maths and rules into our website to give you the most accurate results. Our online calorie calculator will work out how many calories your dog needs per day and how much Vet’s Kitchen food he or she will need to eat. Please keep an eye on our website for a feline version, which will follow shortly.

Further help

If you would like any help working out how much food your pet should have and how many calories they require per day please don’t hesitate to contact on 01793 887555 or or use your Pet Points loyalty points to start a Pet Talk.



S.J. Langley-Hobbs, Ovariohysterectomy. Feline Soft Tissue and General Surgery, 2014