How to Calculate Carbohydrates in a Pet Food

Carbohydrates don’t need to be listed on the label of pet foods in Australia, but we can use a simple calculation to offer us a rough idea. It’s not perfect, and I’ll explain why, but the following method is how to calculate carbohydrates in a pet food:

100 – Protein % – Fat % – Moisture % – Ash %

Here’s a carbohydrate calculator for dog food and cat food for your convenience. If moisture and ash are not listed on your pet food, you may use average values of 10% moisture and 8% ash:


Carbohydrate Calculator


The above calculator will give you a rough idea, but there's a little more to it than that.

Other factors to consider are undisclosed moisture and ash percentages and variance from min & max percentages.

Moisture & Ash

Moisture and ash are usually listed, but as these percentages aren't required to be listed we can use an average 10% moisture and 8% ash for dry food only. Wet foods contain significantly more moisture.

Min & Max

We often find percentages are listed with a guaranteed minimum or maximum. This makes our simple calculation somewhat vague. If a pet food contains Protein (min) 20% then it's possible the protein, on average, is higher.

How to Calculate Carbohydrates: An example

Let's say a dry dog food contains 20% protein, 10% fat, 10% moisture, and 8% ash:

100 - 20 - 10 - 10 - 8 = 52

This product would contain approximately 52% carbohydrates.

So that's it, that's how to calculate carbohydrates in a pet food.

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David D'Angelo

David D'Angelo has worked as a scientist since graduating with a BSc (Hons) in 2000. In addition, David holds a CPD accredited Diploma in Pet Nutrition as well as being CPD accredited VSA (Veterinary Support Assistant). However, his experience and involvement in the pet food industry for 15+ years has given true insight into pet food, formulations, science, research, and pet food marketing. Facebook | LinkedIn | Instagram | Pinterest

8 Comments
  1. Hi! Would this be a similar calculation for cat food? Thanks!

    • Hi T, yes it would.

      Cat foods tend to have higher protein and lower carbohydrates accordingly, but you can use this calculation to get a rough idea.

  2. Hi! I write you this from Mexico City, can you help me with the reference about the Calculate of Carbohydrates? please, or, did you know something about who determinate this calculate?

    • Hi Anna, there are a few variants in a pet food – usually protein and fat are minimum (guaranteed analysis) or average (typical analysis), and often moisture and ash aren’t listed. Therefore carbohydrates can only be estimated, but these will be what remains after protein/fat/moisture/ash are deducted.

  3. I would like a review of aldi natural elements dog food specifically chicken salmon sweet potato & spinach recommended for all breeds & sizes includes puppies I f ibid it hard to believe one size fits all life stages thank you so much Eric

  4. I’ve used “Petfood Reviews” over a number of years now.
    It’s my doggie bible. If a new food appears that takes my interest and I don’t find it on here – I send them a message and ask for a review. I always get a response.
    I have two dogs with two very different allergy problems, so it’s important for me and my dogs to keep on track with what I am putting into their bodies.
    Thank you Petfood Reviews

    • Reply
      Pet Food Reviews (Australia) April 25, 2022 at 8:42 pm

      Thanks for the feedback Libby and I’m glad I’ve always replied – I’m actually terrible at replying to people!!

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