Pet Food Portion Calculator

How to calculate daily pet calories?

Calculating the right amount of food starts with understanding your pet's Resting Energy Requirement (RER)—the energy needed for basic bodily functions—and their Daily Energy Requirement (DER), which adjusts for their lifestyle, age, and activity level.

RER = 70 × (weight in kg)^0.75
DER = RER × activity factor

Using the calculator: an example

A 20kg adult dog with typical activity needs about 890 kcal/day.

Step-by-step calculation:

1. Calculate RER: Use the weight-based formula to find the baseline calories.
2. Apply Activity Factor: Multiply the RER by a factor (e.g., 1.6 for neutered adults) to get the DER.
3. Divide by Food Density: Divide the DER by the calories per gram or cup provided on your pet food label.

Frequently Asked Questions

Can I use this for prescription diets?
Consult your veterinarian before using any calculator for medical-specific nutrition.

How often should I re-calculate?
Recalculate every 3–6 months or after any significant change in weight or energy level.

What if my pet is overweight?
Calculations should be based on your pet's ideal target weight rather than their current weight.