Dog Food Calculator

Working out how much to feed your dog can be confusing, especially with feeding guides on packaging often giving wide ranges. This calculator uses your dog's weight, activity level and the energy content of their food to give you a general daily portion estimate as a helpful starting point.

How to use the dog food calculator

Enter your dog's weight in kilograms, choose the activity level that best matches their lifestyle, and enter the energy content of their food in kcal per 100g, which you will find on the packaging. The calculator estimates their daily energy needs and converts that into an approximate daily amount of food in grams.

How the calculation works

The calculator starts with a resting energy requirement, using the standard veterinary formula of 70 multiplied by your dog's bodyweight in kilograms raised to the power of 0.75. This resting figure is then multiplied by an activity factor depending on your dog's lifestyle, ranging from 1.0 for a supervised weight loss plan up to 3.0 for a growing puppy. Finally, the daily energy figure is divided by your food's energy content and multiplied by 100 to get a daily amount in grams.

Worked example

For an 18kg neutered dog with normal activity, resting energy requirement works out as 70 × 18^0.75 ≈ 612 kcal. Using the neutered, normal activity multiplier of 1.6, daily energy needs come to around 979 kcal. If their food contains 350 kcal per 100g, that works out as (979 ÷ 350) × 100 ≈ 280g of food per day, typically split across two meals.

Splitting portions across the day

Most adult dogs do well on two meals a day, so you would generally split the daily total roughly in half for a morning and evening feed. Puppies often need more frequent, smaller meals, sometimes three or four times a day, to support steady growth without overloading their digestive system in one sitting. If you are changing your dog's food or portion size, doing so gradually over a week or so, mixing old and new food, tends to be gentler on their digestion than an abrupt switch.

Common mistakes people make

A common mistake is following the feeding guide on the packaging without adjusting for your dog's actual activity level, since these guides are often based on an average, moderately active dog. Another mistake is not adjusting portions as your dog ages, gains or loses weight, or their activity level changes, since a portion that suited them a year ago may no longer be right. It is also easy to overlook treats and table scraps when totting up daily intake, which can add up to a significant proportion of daily calories without you realising.

Related calculators

Curious how your dog's age compares to human years? Try our dog age calculator. If you have a cat too, our cat age calculator works the same way for feline ages. When comparing bulk bags or multipack deals on food, our discount calculator can help you work out the real saving on a per-kilogram basis. If you have a cat as well, our cat food calculator works the same way for feline portions.