Food & Cooking⏱ 4 min read
How to Calculate the Right Amount of Food for Your Dog
Feeding guides on dog food bags are often overestimates — calibrated for working dogs, not typical pets. Here is how to calculate the right portion for your dog's weight, age, and activity level.
Canine obesity affects an estimated 50% of UK dogs, and overfeeding is the primary cause. Most owners trust the feeding guide on the bag — which is almost always too generous for the average house dog.
Why Bag Guides Overestimate
Dog food feeding guides are set for "average adult dogs"
assumed to be moderately active.
Most pets:
- Are less active than working or highly active dogs
- Are neutered (neutering reduces calorie needs by ~20-25%)
- May be overweight already (feeds based on current weight, not ideal)
The correct base: feed to your dog's IDEAL body weight,
not its current weight if it is overweight.
For a dog 20% overweight:
Current weight: 18kg
Ideal weight: 15kg
Base feeding calculation on 15kg, not 18kg.
Resting Energy Requirement (RER)
RER (kcal/day) = 70 x (Body weight in kg)^0.75
This is the energy needed at complete rest.
Also written as: RER = 70 x kg^0.75
Examples:
5kg dog: 70 x 5^0.75 = 70 x 3.34 = 234 kcal/day
10kg dog: 70 x 10^0.75 = 70 x 5.62 = 394 kcal/day
20kg dog: 70 x 20^0.75 = 70 x 9.46 = 662 kcal/day
35kg dog: 70 x 35^0.75 = 70 x 14.32 = 1,002 kcal/day
Daily Energy Requirement (Maintenance)
Multiply RER by a life stage / activity factor:
Neutered adult, inactive: x 1.4
Neutered adult, moderate activity: x 1.6
Intact adult, moderate activity: x 1.8
Very active / working dog: x 2.0-3.0
Growing puppy (4 months+): x 2.0-3.0
Gestating female (last 3 weeks): x 3.0
Lactating female: x 4.0-6.0
Example: 15kg neutered adult, moderate activity
RER = 70 x 15^0.75 = 70 x 7.62 = 533 kcal/day
DER = 533 x 1.6 = 853 kcal/day
Converting to Grams of Food
Check the kcal content of your dog food:
Dry kibble: typically 300-450 kcal per 100g (check label)
Wet food: typically 70-120 kcal per 100g (check label)
Example: 400 kcal/100g kibble, dog needs 853 kcal/day
Grams needed = 853 / (400/100) = 853 / 4 = 213g per day
Typical bag recommendation: ~280g for 15kg dog
Actual calculated need: 213g
Overfeeding by bag guide: 31%
Always weigh food — a "cup" varies enormously by kibble density.
Adjust up or down based on body condition scoring every 2-4 weeks.