Pet Food Calculator (Daily Calories & Cups)
Estimate a dog or cat's daily calorie needs and cups of food from weight and life stage, using the veterinary RER/MER formula. Runs in your browser.
Daily feeding
- Resting energy (RER)
- 394 kcal/day
- Daily calories (MER)
- 630 kcal/day
- Cups of food per day
- 1.80 cups
Calories use the veterinary RER formula 70 × (weight kg)^0.75, scaled by a life-stage factor (WSAVA / AAHA). Cups assume the kcal/cup you entered — check your food's label, as energy density ranges widely (≈300–500 kcal/cup). Individual needs vary; confirm with your vet, especially for weight-loss plans, puppies/kittens, or medical conditions. Not veterinary advice.
About this tool
How much to feed a pet starts with how many calories it needs, and veterinary nutrition has a standard way to estimate that. First the resting energy requirement (RER) — the calories to maintain basic body function at rest — is calculated as 70 times body weight in kilograms raised to the 0.75 power, an allometric formula from WSAVA and AAHA guidelines. That is then multiplied by a life-stage and activity factor — lower for neutered adults or weight loss, higher for intact, active, or growing animals — to give the maintenance energy requirement (MER), the daily calorie target. Finally, dividing by the energy density of your food (calories per cup) converts that into cups per day. The calorie math is well grounded; the cups figure is only as accurate as the kcal-per-cup you enter, which varies a lot between foods (roughly 300–500 kcal/cup), so always check your bag's label. Individual pets vary with metabolism, body condition, and health, and weight-loss or growth plans need veterinary oversight. It is informational, not veterinary advice. Everything runs in your browser.
How to use it
- Choose dog or cat and enter the current weight.
- Select the life stage or activity level.
- Enter your food's energy density (kcal per cup) from the label.
- Read the daily calories and cups, and confirm with your vet.
Frequently asked questions
- How are a pet's daily calories calculated?
- Resting energy (RER) = 70 × (body weight in kg)^0.75. Daily need (MER) = RER × a life-stage/activity factor — for example 1.6 for a neutered adult dog, 1.2 for a neutered adult cat, higher for active or growing animals, lower for weight loss.
- Why do I need to enter calories per cup?
- Pet foods differ enormously in energy density — from roughly 300 to over 500 kcal per cup — so cups cannot be estimated from weight alone. The figure is on your food's label or the manufacturer's site; entering it makes the cups accurate.
- What is the difference between RER and MER?
- RER is the calories needed at complete rest. MER (maintenance energy requirement) multiplies RER by a factor for activity, life stage, and neuter status to reflect real daily expenditure. MER is the number you feed to.
- How do I feed for weight loss?
- Weight-loss plans typically target RER (or RER based on ideal, not current, weight) — the factor of 1.0 or below. Because under-feeding can be risky, especially for cats, design weight-loss programs with your veterinarian and monitor body condition.
- Do puppies and kittens need more?
- Yes, considerably — growth requires much higher factors (often 2–3× RER), tapering as they mature. Use the puppy/kitten option as a rough guide and follow your vet's and the food maker's growth feeding charts.
- Is this veterinary advice?
- No. It is an informational estimate based on standard formulas. Confirm feeding amounts with your veterinarian, particularly for growth, weight loss, pregnancy, or any medical condition.