Key takeaways
- Daily food = calorie needs ÷ calories per cup of your food.
- Calorie needs come from resting energy × an activity factor (MER).
- A 40 lb neutered adult ≈ 980 kcal/day ≈ 2.8 cups at 350 kcal/cup.
- Puppies, pregnancy, and illness change needs a lot — ask your vet.
How to work out how much to feed your dog
Feeding amount is really a calorie question. Vets estimate a dog's resting energy requirement (RER) from body weight, then multiply by a factor for activity and life stage to get the maintenance energy requirement (MER) — the calories a dog needs in a day. Divide that by the calories in one cup of your food and you have cups per day. This avoids the guesswork of generic "feed 1 cup per 20 lb" charts, which ignore activity and the real calorie density of your bag.
The activity factor is the lever that matters most: a couch-resting senior and a working sled dog of the same weight can differ more than two-fold in daily calories.
Worked example: a 40 lb neutered adult
40 lb ÷ 2.2046 = 18.14 kg. RER = 70 × 18.140.75 ≈ 615 kcal. MER = 615 × 1.6 ≈ 984 kcal/day. At a food with 350 kcal per cup, that's 984 ÷ 350 ≈ 2.8 cups per day, ideally split into two meals.
Activity / life-stage factors (MER)
| Option | Factor | When it applies |
|---|---|---|
| Weight loss | 1.0 | Reducing weight under vet guidance |
| Senior / inactive | 1.2 | Older or low-activity adult |
| Neutered adult | 1.6 | Typical spayed/neutered pet (default) |
| Intact adult | 1.8 | Un-neutered adult at normal activity |
| Active / working | 2.5 | High daily exercise or working dog |
| Puppy | 3.0 | Growing puppy (rough starting point) |
What to do with the number
Treat the result as a starting ration and adjust to keep your dog at a lean body condition. To check the calorie math on its own, use the dog calorie calculator, and make sure fresh water keeps pace with food using the dog water intake calculator. Re-weigh every few weeks and tweak portions if your dog gains or loses condition.
Frequently asked questions
How much should I feed my dog?
Estimate daily calories from weight and activity, then divide by your food's calories per cup. A 40 lb neutered adult ≈ 980 kcal/day ≈ 2.8 cups at 350 kcal/cup. Confirm with your vet and the label.
How do I read the calories on the bag?
Find the "calorie content" statement (kcal/cup or kcal/kg) and use the kcal-per-cup figure here. If only kcal/kg is given, divide by the cups in a kg of that food.
How much should a puppy eat vs an adult?
Puppies need far more per pound — often 2–3× adult maintenance for their size. Use the Puppy factor (3.0) as a rough start, then follow your puppy food's growth chart and your vet.
How does activity change how much I feed?
Activity sets the MER factor: ~1.6 neutered adult, 1.8 intact, up to 2.5 active/working, and ~1.0 on a weight-loss plan. More activity means more cups per day.
Wet food or dry food?
Both can be complete and balanced. Wet food has far fewer calories per cup (mostly water), so you feed more volume. Always use that product's printed calories per cup.
Should I split it into two meals?
Yes — two meals a day suits most adult dogs; puppies need 3–4 smaller meals. Divide the daily cups figure evenly across them.
Energy method (RER = 70 × kg0.75, MER = RER × factor) follows AAFCO and NRC veterinary nutrition standards — see WSAVA / AAFCO feeding guidance. Reviewed by a veterinarian.
Last reviewed June 2026