Pet Food Math – Kcals Per Ounce

Pet Food Math?

All you ever wanted to know about your pet food label in numbers

Calculating Carbohydrates – Part 2

How many calories are there per ounce of food?

These days, most people take at least a little time to skim over the back of their pet’s food package. Generally, people use the guideline on the back of the package to determine how much to feed their pet and never think much more about it.

Well, those are the days of the past. Lab testing has shown that the recommended feeding on the average chart can suggest as much as 25% more food than your pet needs to eat.  This could contribute to obesity, diabetes, or cancer.  And its certainly an unnecessary strain on your pocketbook and backyard poo spot! … it’s a huge financial perk for manufacturers.

Pet parents are becoming more and more educated about what they are feeding their beloved family members. When you understand the math of pet food labels you become empowered to make better choices for your pets’ health and your budget. Math can seem a bit daunting, but I’m going to break it down so that its easy! I’m also going to make sure that you learn how to do the math regardless of what type of food you’re feeding.  Just like with any equation, we have to go in order to get the answers we’re looking for.

There are two ways to find out how many calories there are in one ounce of the food you purchased. Both methods are taught here. I’ll give you the easy method first. The second method is the default method just in case the food you purchased doesn’t state the information you need in order to do it the easy way.

Method #1: The EASY WAY

Crude Protein (min)24%
Crude Fat (min)7%
Crude Fiber (max)4%
Moisture (max)10%

3,973kcals/kg, 451kcals/cup

This Guaranteed Analysis example will follow us along.

If you look just below the Guaranteed Analysis on any pet food package it should show the “kcals/kg” and the “kcals/cup.” (If it doesn’t, you may have a brand that doesn’t understand or possibly adhere to regulations. That may increase risks associated with using the food).

One “kg,” or kilogram, is 2.2lbs or 35.2lb
(2.2(lbs) x 16(oz/lb) = 35.2(oz/kg))

If you divide the number of calories in a kg by 35.2 you’ll have the number of calories in 1oz!

In the case of this Guaranteed Analysis, that would be:
3,973 / 35.2 = 113 kcals/oz

Method #2: The Long Way

If it doesn’t say how many calories are in a kg, you’ll have to calculate it yourself. You’ll have to use the Guaranteed Analysis for this.

Crude Protein (min)24%
Crude Fat (min)7%
Crude Fiber (max)4%
Moisture (max)10%

Step 1:
Figure out the carbohydrate content in the food.  This was covered in Part 1 of this series. If you just need a quick refresher, with this Guaranteed Analysis that would look like:

  • 24 (protein) + 7 (fat) + 4 (fiber) + 10 (moisture) = 45
  • 100 (% of the product) – 45 (% of the product that’s accounted for) = 55% carbohydrates.

Step 2:
Now we can calculate the total calories using the guaranteed analysis.

You’ll need this guideline. Fat contains more calories per gram than other macronutrients. Calories per gram looks like this:

Protein4 Calories per gram
Fat9 Calories per gram
Fiber4 Calories per gram
Carbohydrates4 Calories per gram

To figure out how many calories are in 100 grams we have to multiply the percentage of each macronutrient (protein, fat, fiber, carbs) by the number of calories of each per gram.

If you can remember to multiply in the order of 4, 9, 4, 4 somehow, it makes this part much easier. *

From Guaranteed AnalysisCalories per gramEQUALS
Protein24%multiplied by4= 96kcals/g
Fat7%multiplied by9= 63kcals/g
Fiber4%multiplied by4= 16kcals/g
Carbohydrates55%multiplied by4= 220kcals/g
Let’s add our answers together:96 + 63 + 16 + 220 =395
*For more advanced feeders, we will discuss fiber calories, Atwater modification and absorption in a later post.

This number represents the calories (kcals) for every 100 grams of food (which is 3.5oz). In this case, we have 395 calories for every 100 grams, or 3.5oz, of food. Why? Because if you google how many ounces 100 grams is, it says 3.5 ounces. Thank God for Google! J Also, because of the math on the right.

In a later post, I will cover why it’s important to know grams and ounces.

Guaranteed Analysis = 100%
= based on 100 gram amount
1oz = 28.57 grams
100 / 28.57 = 3.5oz
= There are 3.5oz in 100 grams, or 100% of the Guaranteed Analysis amounts.

You can scale this up to determine how many oz of each macro-nutrient in a bag.

Step 3:
Now we know there are 395kcals in 3.5oz (or 100 grams).
If you divide 395(kcals) by 3.5(oz) you will get the number of calories in one ounce of the food you purchased.

395 / 3.5 = 113kcals/oz

Click “Next Post” for Part 3
How many ounces are in a cup?

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