APOP Veterinary RER & MER Calculator
RER = 70 × (BW kg0.75) • Estimated MER = RER × selected activity / life-stage factor
Current-weight starting estimatePet Details
Enter the patient’s weight as measured today. RER and the selected activity / life-stage estimate are calculated from this current weight. This tool does not determine target or ideal weight.
Select the range that best matches the patient. These are broad clinical starting ranges, not fixed prescriptions.
This selection provides a current-weight reference only. It is not an individualized weight-loss prescription. Use the APOP Step-Based Weight Loss Planner to incorporate estimated ideal weight, BCS, MCS, step-start RER, the selected rate of weight loss, feeding amounts, and scheduled reassessment.
Build a Step-Based Weight-Loss PlanFeeding (optional)
Use the kcal/cup or kcal/can figure printed on the diet label.
When enabled, treats are capped at 10% of daily calories and the per-feeding amount drops to match, so treats come out of the daily total rather than adding to it.
Results
These guidelines were prepared by the Association for Pet Obesity Prevention (APOP) and represent the consensus of veterinary experts in pet obesity management. They are intended to serve as a guideline only. The recommendations should not be interpreted as dictating an exclusive protocol, course of treatment, or procedure. Variations in practice may be appropriate based on the needs of individual patients, the professional judgment of the veterinary team, and the resources and limitations of each practice setting.
This tool is intended for veterinary professionals and calculates RER and estimated MER from current body weight using the selected activity / life-stage range. It does not determine target weight, diagnose obesity or clinical obesity, or create an individualized weight-loss prescription.
Clinical obesity context MOD, the Three A’s, references, and review information
The MOD is the WPOA general-practice screening and monitoring set used when obesity-focused assessment is indicated. It includes:
- Body-weight trend, Body Condition Score, and Muscle Condition Score
- Structured nutritional history
- Physical examination
- Complete blood count
- Serum chemistry profile
- Urinalysis
A BCS of 7/9 or higher, rapid weight gain, or suspected adiposity-related dysfunction should prompt establishment or review of the MOD. The MOD helps identify abnormalities that may require follow-up, but it does not establish clinical obesity by itself.
Clinical obesity is classified using Adiposity, Abnormality, and Attribution. Confirmed excess adiposity, a clinically meaningful abnormality, and a plausible relationship between the two must be documented in the individual patient.
Weight management may begin while assessment is completed. Interpret the calculator result with current intake, body-weight trend, BCS, MCS, nutritional history, physical examination findings, health status, and measured response over time.
- American Animal Hospital Association. 2021 AAHA Nutrition and Weight Management Guidelines .
- World Pet Obesity Association. Clinical Obesity Framework: Minimum Obesity Database and Three A’s .
The RER equation and general nutritional-assessment context are supported by the AAHA guidelines. MOD and Three A’s terminology follows the WPOA Clinical Obesity Framework. The activity and life-stage ranges displayed by this calculator remain the existing APOP clinical starting ranges and are not presented as an exact reproduction of every category in an external table.