How Much to Feed a Mastiff
Daily food for an adult Mastiff depends on weight, spay/neuter status, and the calories in your specific food. The table below runs the veterinary energy formulas across this breed's AKC weight range.
| Adult weight | Spayed/neutered | Intact |
|---|---|---|
| 120 lb | 2,244 kcal · 6 cups | 2,525 kcal · 6.75 cups |
| 175 lb | 2,978 kcal · 8 cups | 3,351 kcal · 8.875 cups |
| 230 lb | 3,656 kcal · 9.75 cups | 4,113 kcal · 11 cups |
Daily totals from the veterinary RER × MER method, assuming 375 kcal/cup dry food (a mid-range default — your bag will differ; check its calorie statement). Cups shown split across the day.
Get portions for your dog's exact weight and food
Feeding a giant-class dog
Energy needs scale with body weight, not with a flat cup measurement. Veterinary nutrition guidelines calculate resting energy requirement (RER) by raising body weight in kilograms to the 0.75 power and multiplying the result by 70 (Merck Veterinary Manual). This formula works for dogs of any size, but it means a giant-class dog needs meaningfully more total energy than a smaller dog, even though the increase is not a simple one-to-one match with the difference in pounds.
Puppies of this class need higher multipliers on top of that baseline because growth itself takes energy, separate from maintaining an adult body. Merck's guidance sets the multiplier at 3.0 times RER for puppies under 4 months old and 2.0 times RER from 4 to 12 months. Giant-class puppies also stay in this elevated growth window longer than smaller dogs. Research anchors point to giant-breed puppies reaching about half their adult weight around week 26, roughly twice the age it takes a toy-breed puppy to hit that same mark, so the higher multiplier applies over a longer stretch of the puppy's life. Because kcal per cup varies by formula and brand, the same scoop can deliver very different calories depending on the bag, so check the calorie content statement on the specific product. Ribs that are easy to feel and a visible waist say more about whether the amount is right than any bowl-size rule does.
Puppies eat differently
A Mastiff puppy needs far more energy per pound than an adult — published multipliers run 3.0× resting energy under 4 months and 2.0× from 4 to 12 months, against 1.6× for a typical neutered adult. Use the food calculator with the puppy life stage selected, and read our puppy feeding guide for the full picture.
Common questions
How many cups a day for a Mastiff?
At a mid-range adult weight, the table above shows the daily total at a typical dry-food calorie density. The honest answer depends on your bag's kcal/cup — two foods can differ by 25% or more.
My dog is gaining weight on these amounts. Now what?
Published tables put easy gainers at a lower multiplier (1.2–1.4× resting energy). Step down gradually, use body condition checks, and involve your vet.
Starting points, not prescriptions, and not veterinary advice. Formulas and sources: methodology.