MER Calculator (Maintenance Energy Requirement)
Calculate your dog or cat's actual daily feeding calorie target based on weight, age, activity, and spay/neuter status.
Awaiting Details
Enter your pet's details to see their MER.
The MER Formula
Maintenance Energy Requirement multiplies RER by a factor reflecting life stage, spay/neuter status, and activity level, following the ranges commonly cited by veterinary nutritionists.
MER is the number to use as your pet's actual daily feeding target. For puppies and kittens under a year old, use our dedicated Puppy & Kitten Feeding Calculator, which applies growth-specific multipliers.
Frequently Asked Questions
What is Maintenance Energy Requirement (MER)?
MER is the actual number of calories a pet needs per day to maintain their current weight, accounting for activity level, life stage, and spay/neuter status. It's calculated by multiplying RER by a factor that reflects those variables.
Why does spay/neuter status affect MER?
Spayed and neutered pets tend to have a lower metabolic rate than intact pets of the same weight, so veterinary feeding guidelines apply a lower multiplier for altered pets to avoid overfeeding.
What factor should I use for activity level?
Low activity suits mostly indoor, sedentary pets; moderate suits pets with regular daily walks or play; high activity suits working, highly active, or athletic dogs and cats. When unsure, start with moderate and adjust based on weight trend.
How is MER different from the RER Calculator?
RER is the resting metabolic baseline. MER takes that baseline and multiplies it by a life-stage/activity factor to estimate actual daily feeding calories -- MER is the number you should use to decide how much to feed.
Medical Disclaimer
This tool provides general, educational estimates and is not a substitute for professional veterinary advice, diagnosis, or treatment. MER is a starting estimate. Monitor your pet's body condition and weight over time and adjust calories with guidance from your veterinarian. Always consult your veterinarian about your pet's specific health needs before making changes to their diet, water intake, or care routine.
Related Tools
RER Calculator
See the resting metabolic baseline MER is built from.
Calorie Calculator
Find your pet's daily calorie needs based on weight and activity.
Food Portion Calculator
Convert calories into cups or grams per day.
Daily Macronutrient Calculator
Estimate daily protein, fat, and carbohydrate needs.
How This Calculator Works
Read the full breakdown of the formula, sources, and how to interpret your result.