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How much to feed a cat

Written by Mara |

How much can a cat eat? This is a question we get asked often. Unfortunately, there’s no one-size-fits-all answer. The right amount depends on many factors. We’ll explain what these factors are and how you can calculate the right portion for your cat based on their food. We also provide tips to make this easier, along with a feeding guide with average portion sizes. Read on to learn more!

Red cat eating

How do you know how much your cat can eat?

The amount your cat should eat depends on their energy needs. This may sound simple, but a cat’s energy requirements can vary greatly. They are influenced by:

  • Your cat’s life stage
  • Their activity level
  • The cat’s breed
  • Their physical condition
  • Any underlying illnesses

What does your cat’s energy requirement depend on?

Your cat’s life stage

A kitten has a higher energy requirement than an adult cat. They also need more protein, vitamins, and minerals to support their growth. However, their stomach capacity is much smaller. That’s why it’s important for kittens to receive specially adapted nutrition.

Older cats also have different dietary needs. Since many senior cats become less active, their energy requirements are often lower. However, they still need sufficient vitamins, minerals, and high-quality protein to maintain muscle mass. Additionally, senior cats benefit from easily digestible food. That’s why it’s advisable to switch to senior cat food at a certain age.

Your cat's activity level

A cat that goes outdoors often uses more energy than an indoor cat that spends most of the day sleeping.

Cat food packaging usually indicates how much to feed based on your cat’s weight, often providing a range between two amounts. For an indoor cat with low activity levels, start with the lower amount. An outdoor cat can be given the higher amount.

After about two weeks, it’s a good idea to check your cat’s weight and adjust the feeding amount if necessary based on any changes.

The cat’s breed

Some cat breeds have a higher metabolism than others, which influences the amount of food they need. Additionally, certain breeds, like the Norwegian Forest Cat, grow quite large. This means they have a higher nutritional requirement compared to smaller breeds.

The cat's physical condition

Do you have a cat that is on the lean side? Your cat may have a higher energy requirement and need more food. If your cat is overweight, you might be feeding too much or offering too many extras alongside their regular meals.

It’s usually safe to feed slightly less than the amount recommended on the packaging, but never reduce it to less than 70% of the suggested portion. Otherwise, your cat may develop nutrient deficiencies. If your cat is overweight, it’s better to switch to a food with an adjusted energy content. This way, you can feed according to their energy needs while ensuring they still receive enough protein, vitamins, and minerals to lose weight while maintaining muscle mass.

Keep in mind that neutered cats have a lower energy requirement than intact cats, so you should consider this when determining portion sizes.

Any underlying illnesses

A cat with a medical condition has different nutritional needs than a healthy cat. The body often has to work harder, requiring more energy. Since appetite can sometimes decrease during illness, a specially adapted diet with a higher energy content is often necessary.

Relevant products

What is a cat’s energy requirement?

When determining a cat’s energy needs, we look at metabolisable energy—the energy a cat can use for bodily processes such as growth and muscle development. Cats also lose energy through urine and faeces, which is accounted for in metabolisable energy.

A Cat’s Metabolic Weight

A cat’s energy requirement is calculated based on metabolic weight, which considers the surface-to-volume ratio of an animal. Smaller animals have a higher energy requirement than larger ones.

You can calculate a cat’s metabolic weight by raising their body weight to the power of 0.67 (kg⁰·⁶⁷). For example, a 4 kg cat has a metabolic weight of 2.53.

Energy requirement of a cat

The energy requirement of a neutered and/or indoor cat

A neutered cat and an indoor cat have a lower energy requirement than an active outdoor cat. According to European guidelines, the energy requirement (MER) is estimated at 52–75 kcal ME/kg⁰·⁶⁷ or 215–314 kJ ME/kg⁰·⁶⁷.

The energy requirement of an active outdoor cat

An active outdoor cat has a higher energy requirement. According to European guidelines, the energy requirement (MER) is estimated at 100 kcal ME/kg⁰·⁶⁷ or 418 kJ ME/kg⁰·⁶⁷.

The energy requirement of a growing kitten

A kitten has different energy requirements than an adult cat. In this case, we consider a cat between 0 and 12 months to be a kitten.

This period can be divided into three phases, each with a different energy requirement:

  • Kitten up to 4 months old: Adult cat energy requirement (MER) × 2–2.5
  • Kitten between 4 and 9 months old: Energy requirement (MER) × 1.75–2
  • Kitten between 9 and 12 months old: Energy requirement (MER) × 1.5

How much energy does cat food contain?

As you can imagine, every cat food has a different composition and therefore a different energy content. The energy content is not always listed on the packaging, but luckily, you can calculate it yourself.

The energy content of a food is determined by the amount of crude protein, crude fat, and digestible carbohydrates it contains. These values can be found in the food’s analysis. Carbohydrates are often not listed but can be calculated manually. The analysis also includes crude ash (minerals) and crude fibre, which do not provide energy but are needed for the energy calculation.

How do you calculate the energy content of cat food?

How much energy do the macronutrients in cat food provide?

The macronutrients protein, fat, and carbohydrates provide energy to the body in the following amounts:

  • Protein: 4 kcal ME or 16.7 kJ ME × %
  • Fat: 9 kcal ME or 37.6 kJ ME × %
  • Carbohydrates: 4 kcal ME or 16.7 kJ ME × %

How do you calculate the amount of carbohydrates in cat food?

Because digestible carbohydrates (NFE) are often not listed on the packaging, you need to calculate them yourself. Here’s how:

Total Carbohydrates = 100 – (% protein + % fat + % moisture + % ash)

Digestible Carbohydrates (NFE) = Total Carbohydrates – % crude fibre

These digestible carbohydrates are then included in the calculation of a food’s energy content.

How do you calculate the energy content of a food?

To calculate the energy content of a food, you need the percentage of macronutrients in the food. These can be found in the analytical constituents of cat food.

Example:

Vetality Adult – Cat Food contains the following analytical constituents:

  • Crude protein: 32%
  • Crude fat: 14%
  • Crude ash: 6%
  • Crude fibre: 3%
  • NFE: 36% (calculated)
  • Moisture: 9%

The energy content of this food is then calculated as follows:

(4 × 32) + (9 × 14) + (4 × 36) = 128 + 126 + 144 = 398 kcal ME /100 g of food or 1662 kJ ME /100 g of food.

How much of a food can my cat eat?

Above, we calculated the energy content of Vetality Adult – Cat Food.

Now, let’s say you have a 4 kg adult cat that spends a lot of time outdoors and maintains a healthy weight. The energy requirement for an active outdoor cat is 418 kJ ME/kg⁰·⁶⁷.

For a 4 kg cat, this is 418 kJ × 4⁰·⁶⁷.

The metabolic weight of a 4 kg cat is 4⁰·⁶⁷ = 2.53.

So, a 4 kg cat has an energy requirement of:
418 × 2.53 = 1058 kJ per day.

The food in the example has an energy content of 1662 kJ ME per 100 g.

This means the cat can eat (1058/1662) × 100 = 64 g per day of this food.

How much food can my cat eat per day?

The amount of food your cat needs depends on many factors. Don’t feel like calculating it yourself? Or does the calculation seem too complicated?

Start by using the feeding guide on the food packaging:

  1. Weigh your cat.
  2. Choose the recommended portion based on their weight.
  3. Feed this amount for two weeks.
  4. Weigh your cat again after two weeks.
    • Has your cat lost weight? Increase the food amount by 10%.
    • Has your cat gained weight? Reduce the portion by 5–10%.
    • Is the weight stable? Keep the same feeding amount!

It’s always a good idea to weigh your cat when switching food and at least once a year to monitor any weight changes.

How much food should my cat eat per day if I mix dry and wet food?

If you want to combine wet and dry food, the best approach is to calculate the energy content of both types of food.

Then, decide what proportion of your cat’s daily intake should come from wet food and what proportion from dry food.

Example calculations for the amount of food for a cat

Example calculation 1

Do you feed your cat twice a day and want to give wet food once and dry food once? In this case, 50% of the daily energy intake should come from wet food and 50% from dry food.

  1. Calculate how much wet food your cat would need per day and divide this by 2.
  2. Do the same for dry food.

This way, you’ll know exactly how many grams of wet and dry food to give each day.

Using the feeding guide? Check the daily recommended portion on the packaging of the dry or wet food and simply divide it by 2.

Example calculation 2

Do you want to feed half a pouch of wet food per day (approximately 85 g per pouch)? Then you would give around 40 g of wet food per day.

For example, if your cat’s daily allowance for wet food only would be 200 g, then 40 g equals 20% of the total daily intake. This means you still need to provide 80% of the food in the form of dry kibble.

If the normal daily portion of dry food is 60 g, then you would feed 0.8 × 60 = 48 g of dry food alongside the 40 g of wet food per day.

Feeding chart for an adult cat

A manufacturer is required to state on the packaging how much of the food a cat should eat per day. However, this is just a guideline! You should always adjust the portion size based on your own cat’s needs.

An active 4 kg cat has an energy requirement of 1058 kJ (1.058 MJ) per day. In contrast, an indoor or neutered 4 kg cat has an average energy requirement of 675 kJ (ranging from 544 to 795 kJ) per day.

For example, with Vetality Adult – Cat Food, an indoor cat should only eat (675/1662) × 100 = 40 g per day, compared to 64 g per day for an active 4 kg cat. This shows how much feeding amounts can vary even for the same weight, depending on activity level.

On average, an adult cat can eat:

  • 250–400 g of wet food per day or
  • 35–70 g of dry food per day.

The table below provides calculated feeding amounts for a cat, based on:

For the wet-dry food combination, we assume a wet food pouch of 85 g. The table shows the daily feeding amounts in grams.

Feeding Charts Adult Cat

Feeding Chart Indoor/Neutered Cat

Cat Weight Grams of Dry Food Grams of Wet Food Grams of Dry Food with 1/2 Pouch of Wet Food Grams of Dry Food with 1 Pouch of Wet Food
2 kg 23 111 14 5
2,5 kg 27 129 18 9
3 kg 30 149 21 13
3,5 kg 34 162 25 16
4 kg 37 177 28 19
4,5 kg 40 191 31 22
5 kg 43 205 34 25
5,5 kg 46 219 37 28
6 kg 48 232 40 30

Feeding Chart Active Outdoor Cat

Cat Weight Grams of Dry Food Grams of Wet Food Grams of Dry Food with 1/2 Pouch of Wet Food Grams of Dry Food with 1 Pouch of Wet Food
2 kg 36 174 27 19
2,5 kg 42 202 33 24
3 kg 48 228 39 30
3,5 kg 53 253 44 35
4 kg 58 277 49 40
4,5 kg 62 300 53 45
5 kg 67 321 58 49
5,5 kg 71 343 62 53
6 kg 76 363 67 58

Feeding chart with average feeding amounts

Cat Weight Grams of Dry Food Number of 85 g Meal Pouches Grams of Dry Food with 1 Pouch of 85 g Wet Food
2 kg 35 2 20
3 kg 45 3 30
4 kg 55 3 1/2 40
5 kg 70 4 50
6 kg 80 4 1/2 60

Nutritional advice for your cat

Do you have questions about your cat’s food? Or would you like to know if your cat is getting the right nutrition? Contact us at veterinarian@vetsend.co.uk.