Dog Food Portion Calculator
Calculate how much to feed your dog per day based on body weight and activity level. Shows grams and approximate cups.
How to use this tool
- Weigh your dog or use the last vet measurement.
- Select the activity level that best matches your dog's lifestyle.
- Enter the kcal/100g from the dog-food bag (usually printed in the feeding guide).
- Read the recommended daily grams and approximate cups.
Find the right daily food amount for your dog based on body weight and activity level. The calculator uses the NRC Resting Energy Requirement (RER) formula recognised by veterinary nutritionists.
Not veterinary advice. These results are estimates for general guidance only. Always consult a licensed veterinarian before making health, nutrition, or medication decisions for your pet.
Formula
Resting Energy Requirement: RER = 70 × weight(kg)0.75 kcal/day
Maintenance Energy Requirement: MER = RER × activity_factor kcal/day
Daily food amount: grams/day = MER ÷ kcal_per_100g × 100
Approximate cups: cups = grams ÷ 115
How it works
The calculator uses the veterinary-standard RER formula (70 × BW0.75) to estimate the calories a dog needs at rest, then multiplies by an activity factor to get the Maintenance Energy Requirement. The food weight is derived by dividing MER by the energy density of the chosen food. The cup estimate assumes a standard density of approximately 115 g per 240 ml cup.
The activity factor is supplied by the user (e.g. 1.0 for sedentary, higher values for active dogs). Because cup sizes and food densities vary considerably between brands, the gram figure is more reliable; always confirm with the specific food's feeding guide.
Worked example
Worked example
- Dog weight = 20 kg, activity factor = 1.0 (sedentary/maintenance), food energy = 350 kcal/100 g.
- RER = 70 × 20^0.75 = 70 × 9.457 ≈ 662 kcal/day.
- MER = 662 × 1.0 = 662 kcal/day.
- Food per day = 662 ÷ 350 × 100 = 189 g/day.
- Cups = 189 ÷ 115 ≈ 1.64 cups.
RER 662 kcal/day, MER 662 kcal/day, 189 g/day (approx. 1.64 cups)
Key terms
- RER (Resting Energy Requirement)
- The calories a dog needs to maintain basic physiological functions at rest, calculated as 70 × BW(kg)^0.75.
- MER (Maintenance Energy Requirement)
- The total daily calorie target, equal to RER multiplied by a factor that accounts for activity level, life stage, and health status.
- Metabolic body weight (BW^0.75)
- Body weight raised to the power 0.75, used in energy formulas because metabolic rate scales allometrically rather than linearly with mass.
- Activity factor
- A multiplier applied to RER to account for a dog's daily energy expenditure; typical values range from 1.0 (sedentary) to 3.0 (working dog).
- Energy density
- The caloric content of a food per unit mass, expressed here as kcal per 100 g; higher values mean less food is needed to meet energy requirements.
Frequently asked questions
- What is RER?
- Resting Energy Requirement (RER) is the energy a dog needs at rest in a thermoneutral environment. It is calculated as 70 × weight(kg)^0.75 (the NRC formula).
- What is MER?
- Maintenance Energy Requirement (MER) is RER multiplied by an activity factor (0.8–1.6) to account for lifestyle. This is the target daily calorie intake for most dogs.
- How many grams in a cup of dry dog food?
- Approximately 100–120 g depending on kibble size. This calculator uses 115 g/cup as a middle estimate. Check your food's feeding guide for the exact figure.