Cat Calorie Calculator (Daily Calories per Day)
Estimate how many calories your cat needs daily using RER/MER (weight, goal, activity).
Quick answer
What you’ll get
- RER (Resting Energy Requirement)
- MER / daily calories (RER × factor)
- Optional weight-loss target
Use this as a starting estimate, then adjust based on body condition and weight trend.
Inputs
Use current weight, or ideal weight if your vet recommends.
Split daily calories into meals.
Life stage, goal, and activity (MER factor)
MER (daily calories) = RER × factor. The factor depends on age, lifestyle, and your goal.
Turn on if your vet gave you a specific factor.
Typical factors: ~0.8 (loss), ~1.0–1.4 (adult), ~2.0–3.0 (kittens).
Tips for accuracy
- If your cat is overweight, using ideal weight can be more accurate than current weight.
- Track weight weekly. Adjust calories if weight is changing too fast.
- Kittens often need more calories per pound due to growth.
How this calculator works (formulas)
1) Convert weight to kilograms
kg = lb × 0.453592
2) RER
RER = 70 × (kg0.75)
3) MER (daily calories)
MER = RER × factor
Factor is chosen based on life stage, goal, and activity (or manually entered).
FAQ
What is RER for cats?
RER (Resting Energy Requirement) is an estimate of calories needed at rest: 70 × (body weight in kg^0.75).
What is MER for cats?
MER (sometimes called DER) is daily calories after adjusting RER for life stage, activity, and goal: RER × factor.
How many calories does a kitten need?
Kittens generally need a higher factor than adult cats because they’re growing. This calculator includes a kitten option and lets you adjust meal frequency.