Today, a guest post from Ellyn Grubbe, a former student of mine and a CASI graduate, Ellyn does consultations in her own right now and is one of the most nutrition-savvy dog people I know. She wrote this entry years ago to help members on our yahoo group figure out the foundational calculation of all home made diets; how many calories to feed! We were finding, then as now, people put off by “all the math” and this entry shows how easy it really is. Many thanks to my dear friend for this contribution. Essential for anyone doing home made diet – raw or cooked.




by Ellyn Grubbe


1) The first step with any home- prepared diet, raw or cooked, is to

know how much your dog weighs. If you use your bathroom scale, weigh

yourself first, then pick up your dog and weigh both of you together

and subtract the difference. If your dog is too big to pick up, go to

the vet and use their scale if they will let you do that for free,

mine does. No matter how you get it done, you have to know how much

your dog weighs.



2) Now that you know how much your dog weighs in pounds, you must

convert that weight to kilograms. All calculating and amounts use

the metric system of grams and kilos so there is no getting around

this one, but it is easy enough. Here is what you do:

There are 0.4536 grams to a pound.

Multiply your dogs weight in pounds by 0.4536. That’s it.


One kilogram = 2.2 lbs. So you can also divide your dog weight by 2.2.


An example with my dog would be: 40 lbs multiplied by 0 .4536 =


If you divide you get the same basic result. 40 lbs divided by 2.2 =

18.18 kilograms. I round down to 18 kilograms either way.




When formulating a recipe for your dog, we will be asking you to

think a bit differently about food and recipes than what you are

used to. Instead of thinking cups and amounts, which measure volume,

we are asking you to think about the actual nutrient content of the


To that end, we will be using the National Research Council’s

recently published requirements for canines. These numbers are based

on the

dog’s body weight (BW) in kilos (kg) calculated ” to the power of


This is an important concept to know about because a dog’s nutrient

requirements are not linear to its body weight. What this means is


a 50 lb. dog does not need twice the amount of calories or other

nutrients as a 25 lb dog. Nor do you multiply the requirements of a

25 lb dog by 4 for a 100 lb dog. By following the NRC numbers we are

taking this into consideration, actually thinking in nutrients.

In this way, we can treat our dogs as the unique individuals they

are and feed them accordingly. This may seem confusing at first but


will get easier with time as you work with it.


3) Now that you know how much your dog weighs in kilos, it is


to know how many calories your dog needs to consume every day to


it’s present body weight.

This is surprisingly simple to do.


First find the calculator built into your computer. Open the


click on view and choose the word “scientific”.

– Type the dogs weight in kilograms into the calculator on the


– Click the key with x^y (this does the “to the power of”


– Type in 0.75

– Click the equal sign =. ( the number you get is your dog’s BW to


power of 0.75)

– Multiply that number by 130. The resulting number is how much

metabolizable energy your dog will need to consume(otherwise know as

how many calories your dog needs daily).




My dog weighs 18kg, as we found out in step two.

– 18 x^y 0.75 = 8.73.

– 8.73 X 130 = 1,1349.


-Round the number to 1,135, which is the number of calories my dog

would need.


BW “to the power of 0.75” multiplied by the NRC nutrient value = the

amount of calories and/or a nutrient your dog needs.




My commentary: Thank you Ellyn for explaining the optimal, in my opinion the correct method for starting to calculate a  dog’s nutrient requirements. I would only add that the number  130 is just a starting point and in my practise I have often found it amounts to more than the dog actually requires; for example, a sedentary or senior dog may do best – maintain weight and good energy levels – on as little as 90 calories per unit of metabolic weight.Some very active dogs may need more than 130. In general, when I start the formulation process, I assess what the dog has been used to eating – many raw diets for example are very low in total energy, and it’s a mistake to suddenly bring the calorie level up to 130 “because that’s the text”. Often I find myself starting with 120 or even 110 calories per unit BW, and have the owner monitor progress; is the dog very hungry? Has he or she lost weight? And if it seems too low we simply adjust upwards. The method here is critical; you can’t know your dogs protein, fatty acid, vitamin and mineral requirements without first calculating his or her metabolic weight – you can guess, but I prefer precision. If we’re going to the  trouble of buying, making, storing and supplementing home made food in the first place, why take chances? This method offers real knowledge and control. And it’s not – as Ellyn made so easy to understand – all that difficult, at all. 🙂