How Many Grams of Dog Food a Day? Amounts by Weight and How to Calculate Calories

Dog food comes down to 3 steps: calories → grams

What a dog needs isn't so many grams but so many kcal. For dogs of the same weight, a food at 340 kcal per 100 g and one at 400 kcal call for nearly 20% difference in grams. So first work out the calories needed per day, then convert to grams using the food's calories.

1. 1

   Find the RER (calories needed at rest)

   RER = 70 × (weight in kg)^0.75. For 5 kg, 70 × 5^0.75 ≈ 234 kcal. You can get ^0.75 on a calculator by cubing the weight, then pressing √ twice.

2. 2

   Apply a factor to get the DER (daily calories)

   DER = RER × factor. For a spayed or neutered adult dog it's 1.6, so a 5 kg dog needs 234 × 1.6 ≈ 375 kcal. The factor depends on age, spay/neuter status and activity.

3. 3

   Convert to grams using the food's calories

   Daily amount (g) = DER ÷ kcal per 100 g × 100. For a food at 360 kcal per 100 g, 375 ÷ 360 × 100 ≈ 104 g.

If the bag says "3,600 kcal/kg," divide by 10 to get the per-100 g figure (360 kcal). Use the value labeled metabolizable energy. It's often listed in the same section as the analysis of crude protein and so on, so look on the back of the bag.

Chart of daily calories and food by weight

This table sets out the calculation above by weight. Food amounts are for dry food at 360 kcal per 100 g. If you give treats, subtract them (up to 10% of the day).

The table shows that doubling the weight doesn't double the calories. Per kilogram, a 2 kg dog needs about 94 kcal, a 10 kg dog about 63 kcal and a 30 kg dog about 48 kcal. Smaller dogs must eat a lot for their size, so dividing a large dog's amount by weight and applying it to a small dog leaves it short.

Factors for neutering, age and activity

The factor used in the DER calculation depends on how the dog lives. The table below shows commonly used typical values, and real values vary. If you're unsure, start with the table and adjust by watching changes in weight.

• After spaying or neutering: going from intact (1.8) to spayed/neutered (1.6) cuts calories needed by about 11%. Appetite tends to rise after surgery, which is why dogs gain weight on the same amount.
• Senior dogs: when walks shorten and sleep increases, use 1.4; if they move even less, go down to around 1.2. If an older dog is getting thin, bring the amount back up.
• Active dogs: for dogs that run over an hour daily or do dog sports, start at 2.0. Deciding from weekly changes in weight is more stable than changing the amount between active and quiet days.

For an overweight dog, current weight × factor gives the amount that maintains the excess weight. Calculations for dieting are explained in detail in Diet Plans for Dogs and Cats.

Puppy amounts change greatly with age

Puppies need about twice an adult's calories to build their bodies. Growth is fastest up to 4 months, calculated with a factor of 3.0. Since weight rises weekly, the key is to weigh every 1–2 weeks and recalculate each time.

• Many puppy foods are higher in calories than adult food (around 380–420 kcal per 100 g), so always calculate from the figure on your own bag.
• While the stomach is small, split food into 3–4 meals a day, reducing to 2–3 from around 6 months.
• Switch to adult food at about 10 months for small dogs and about 18 months for large dogs. When growth is nearly over, lower the factor from 2.0 to 1.6–1.8.
• Overfeeding during growth can strain the bones and joints of large dogs. Rather than adding more because "they eat well," judge by body condition (whether the ribs can be felt).

When the bag's feeding guide and your calculation disagree

It's common for the calculated amount to differ from the bag's feeding guide. The bag's chart is a guide assuming an average dog, with coarse weight bands, so ranges tend to be wide, such as "110–180 g for 5–10 kg." For a spayed or neutered dog that lives mainly indoors, the chart's amount can be on the high side.

• Look at both the bag and your calculation, and start in between
• Weigh after 2–4 weeks: reduce by 5–10% if weight has gone up, and increase by 5–10% if it has gone down
• As well as weight, check whether the ribs can be felt under a thin layer of fat and whether there's a waist from above (BCS)

Even at the same weight and age, individual calorie needs vary by about ±20%. Treat the calculated amount as a starting point, and find what suits your dog from changes in weight.

Calculate your dog's amount with the tool

The Dog & Cat Food Portion Calculator does all of these calculations at once.

1. 1

   Choose dog and enter weight and BCS

   BCS is a 9-point body score, with 5 ideal. If your dog is heavy, choose 6–7 to also see an estimated ideal weight.

2. 2

   Choose a lifestyle

   Choose from puppy (up to 4 months, from 4 months), spayed/neutered, intact, senior, very active and so on. If your veterinarian has given you a factor, you can enter it directly.

3. 3

   Enter the food's calories

   You can enter the bag's kcal/100 g or kcal/kg as it is. When mixing in wet food, add a second food.

4. 4

   Choose the treat percentage and meals per day

   You'll see grams per day and per meal. The "Chart by weight" tab lists calories by factor for each weight.

Amounts when mixing dry and wet food are explained in Mixing Dry and Wet Food, and How Much Water, and treat amounts in How Many Treats Can Dogs and Cats Have a Day?

FAQ

How many grams of food should a 5 kg dog eat a day?

A spayed or neutered adult dog needs about 375 kcal a day, or about 104 g of dry food at 360 kcal per 100 g. With 10% of the day as treats, food is about 94 g, or about 47 g per meal with 2 meals. If intact, it's about 421 kcal (about 117 g).

What's the formula for a dog's daily calories?

Find the RER (resting energy requirement) = 70 × (weight in kg)^0.75, then multiply by a factor such as 1.6 for a spayed or neutered adult, 1.8 for an intact dog or 3.0 for a puppy (up to 4 months) to get the daily calories (DER).

The bag's feeding guide differs from my calculation. Which should I trust?

The bag's chart is a guide for an average dog with coarse weight bands, so differences aren't unusual. The reliable way is to start between the two, check weight and body condition every 2–4 weeks and adjust by 5–10% at a time.

How many meals a day should a puppy have?

About 3–4 a day until around 4 months, and 2–3 from around 6 months. The daily amount changes with age and weight, so weigh every 1–2 weeks and recalculate.

How much should I cut food after neutering?

The factor goes from 1.8 to 1.6, so calories needed fall by about 11%. For a 5 kg dog, that's from about 421 kcal to about 375 kcal, or from about 117 g to about 104 g of food at 360 kcal/100 g. Appetite tends to rise after surgery, so adjust while watching the weight.