Wet vs dry dog food: what it really costs

Why price per kg misleads when comparing wet and dry dog food, how to compare on dry matter, and why cost per day is the number that matters.

Facts checked against sources on 26 September 2026 · 5 min read

On this pageHow much is water?Why price per kg misleadsComparing nutrients: use dry matterWorking out cost per daySources

A kilo of wet food and a kilo of dry food aren’t the same amount of food. Most of the difference is water, and water changes every comparison you might make.

How much is water?

Wet dog food is roughly 70–80% moisture; dry food is roughly 8–10%.[1] The industry definitions are 60% moisture or more for wet food and 14% or less for dry.[2] That’s why wet food portions are much bigger.[1]

Why price per kg misleads

Because wet food is mostly water, a dog needs to eat several times more of it by weight to get the same energy. A wet food can look cheap per kg and still cost more per day. The useful comparison is cost per calorie or, better still, cost per day for your dog, not cost per bag, tin or kilo.[5]

Comparing nutrients: use dry matter

The same water problem affects the protein and fat figures on the label, which are given “as fed”. You can’t directly compare nutrients in a wet and a dry food unless you convert them to a dry-matter basis.[3]

  1. Dry matter % = 100 − moisture %.[3]
  2. Nutrient on a dry-matter basis = nutrient % ÷ dry matter % × 100.[4]
Worked example (illustrative numbers): a wet food with 10% protein and 78% moisture has 22% dry matter, so its protein on a dry-matter basis is 10 ÷ 22 × 100 ≈ 45%. A dry food with 26% protein and 8% moisture has 92% dry matter: 26 ÷ 92 × 100 ≈ 28%. The wet food that looked lower in protein is actually higher.

Dry-matter figures tell you about the recipe. What your dog actually takes in each day also depends on how much you feed.[3]

Working out cost per day

  1. Find how many calories your dog needs a day (see our feeding guide).
  2. Divide by the food’s energy per 100 g to get grams per day.
  3. Multiply grams per day by the price per gram.

This only works when the label gives the energy (kcal). Many don’t. On our food pages that shows as “Not on label”, and we don’t estimate it.

Add your dog on this site and every food shows its cost per day, using the cheapest current price we’ve found, excluding delivery. Compare foods by cost per day, or read how much to feed.

Sources

  1. Different types of pet food, UK Pet Food
  2. Code of Good Labelling Practice for Pet Food (October 2019), glossary, FEDIAF
  3. Proteins in Pet Food (fact sheet), UK Pet Food
  4. “Complete and Balanced” Pet Food, US Food and Drug Administration
  5. Make “Cents” of Your Pet Food Budget (Petfoodology, 10 June 2019), Cummings School of Veterinary Medicine, Tufts University

This guide is general information, not veterinary advice. Spotted an error? Tell us.

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