Cat Calorie Calculator
Free, science-based daily feeding calculator using the WSAVA/AAHA Resting Energy Requirement formula. No sign-up, no tracking — all math runs in your browser.
By Paws & Pounds Research Team — reviewed against WSAVA/AAHA guidelines. Last updated .
Quick answer
A healthy adult spayed/neutered indoor cat needs about 20 kcal per pound (45 kcal/kg) of ideal body weight per day. For weight loss, reduce this to about 0.8 × RER (70 × kg^0.75). Split the daily portion across 2–3 meals and aim for no more than 1–2% body-weight loss per week.
Your cat's details
Results update instantly. Nothing is sent to a server — all math happens in your browser.
If unsure, use your vet's target or the breed's healthy midpoint. Enter the same value as current weight to calculate a maintenance plan.
Neutered cats typically need ~20% fewer calories.
Found on the food bag's guaranteed-analysis panel. Provide this to see the daily portion in grams.
Daily feeding plan
Safe weight-loss calorie target.
- Main meals (90%)
- 180 kcal
- Treats max (10%)
- 20 kcal
- RER
- 249 kcal
- DER (maintenance)
- 299 kcal
- Safe pace
- Target max 0.11 kg change per week (~2% of body weight). Estimated 9 weeks to reach the goal.
Estimate only. Individual metabolism varies. Consult your veterinarian before changing your cat's diet — especially for kittens, pregnant queens, or cats with diabetes, kidney disease, or thyroid issues.
How the calculation works
The calculator follows the two-step formula used by veterinary nutritionists worldwide:
- RER (Resting Energy Requirement) = 70 × body-weight-in-kg^0.75. This is the calories your cat would burn simply lying still all day.
- DER (Daily Energy Requirement) = RER × activity factor. Typical factors:
- 1.0 — weight loss
- 1.2 — neutered indoor adult (default)
- 1.4 — intact, very active
- 1.2 × 1.2 — supervised gradual weight gain
The daily calorie target is then split 90% main food / 10% treats. If you enter the food's kcal per 100 g, the calculator converts the main-food kcal into grams so you can weigh it directly on a kitchen scale.
Weight-loss pace: we cap the recommended weekly loss at 2% of body weight — any faster and cats risk hepatic lipidosis, a potentially fatal liver condition.
Frequently asked questions
- How many calories does my cat need per day?
- Most spayed or neutered indoor adult cats need roughly 20 kcal per pound of ideal body weight per day (about 45 kcal per kg). A 10 lb (4.5 kg) cat therefore needs ≈ 200 kcal/day at maintenance. The calculator refines this using the veterinary RER formula (70 × kg^0.75) plus activity and neuter multipliers.
- What formula does this calculator use?
- Resting Energy Requirement (RER) = 70 × body-weight-in-kg^0.75. The Daily Energy Requirement (DER) multiplies RER by a factor of 1.0 for weight loss, 1.2 for a neutered indoor cat at maintenance, or 1.4 for an intact, highly active cat. These multipliers come from the WSAVA Global Nutrition Toolkit and the AAHA Weight Management Guidelines.
- How much should I feed my cat to lose weight?
- Feed roughly 0.8 × RER kcal per day. Expect no more than ~1–2% of body weight lost per week. For a 12 lb (5.4 kg) cat, weight-loss RER ≈ 183 kcal/day. Weigh the food on a kitchen scale, split across 2–3 meals, and recheck weight every 2 weeks.
- Is this calculator accurate for kittens or pregnant cats?
- No. Kittens, pregnant queens, and lactating cats have much higher energy needs (up to 3× RER) and require life-stage–specific plans. Consult your veterinarian for those life stages.
- Why does my cat need fewer calories after being neutered?
- Neutering lowers a cat's basal metabolic rate and increases appetite, reducing maintenance energy needs by roughly 20–25%. Adjusting calories after the procedure is the single most effective way to prevent post-neuter weight gain.
- What's the difference between RER and DER?
- RER (Resting Energy Requirement) is the calories a cat burns at rest, just to stay alive. DER (Daily Energy Requirement) is RER multiplied by an activity/life-stage factor — it's the actual daily calorie target for feeding.
- Do I need a smart scale or vet visit to use this?
- No. Weigh yourself on a regular home scale, then weigh yourself holding your cat, and subtract. Combined with a visual Body Condition Score assessment, this is enough to produce a reliable feeding plan at home.
Want to track progress over time?
The Paws & Pounds app saves every weigh-in, auto-adjusts the calorie target as your cat approaches the goal, lets your household log meals together, and charts the trend so you can show your vet.
Sources & further reading
- WSAVA Global Nutrition Toolkit — Calorie Calculation & Body Condition Assessment — World Small Animal Veterinary Association, 2021
- 2014 AAHA Weight Management Guidelines for Dogs and Cats — American Animal Hospital Association, 2014
- Nutrient Requirements of Dogs and Cats — National Research Council (NRC), 2006
- AAFP Feline Life Stage Guidelines — Nutrition and feeding recommendations — American Association of Feline Practitioners, 2021