Dog calories: the exact formula against the 30 x weight + 70 shortcut

A healthy, neutered adult dog needs about 1.6 times 70 times its weight in kilograms to the 0.75 power—so a 10 kg dog needs about 630 kcal, and a 30 kg dog about 1436 kcal a day [1]. The shortcut formula, 30 times weight plus 70, is close for mid-sized dogs but overestimates calorie needs by 326 kcal (16.8%) for dogs at 45 kg [1]. The difference matters most for large dogs and for anyone using automatic feeders or calorie tracking.

The MSD formula: 1.6 × 70 × (weight in kg)^0.75

The MSD Veterinary Manual gives this formula as a starting point for healthy adult dogs, and says it can be used at any body weight [3]. MSD gives the resting energy requirement as RER = 70 × (weight in kg)^0.75 and the daily need of a neutered adult as 1.6 × RER [3]. Combined, that is: Daily calories = 1.6 × 70 × (weight in kg)^0.75

This means that as a dog's weight increases, its calorie requirement grows, but not in a straight line. For example:

This formula accounts for the fact that a larger dog does not need calories in direct proportion to its weight. Instead, the need is proportional to weight raised to the 0.75 power—a curve, not a line [1,3].

The shortcut formula and where it drifts

The shortcut, 30 × (weight in kg) + 70, stands in for the resting requirement, 70 × (weight in kg)^0.75 [3]. The MSD Veterinary Manual allows it only for animals over 2 kg and under 45 kg [3]. Inside that range it is within 2.5% from 15 to 20 kg, 6.0% low at 5 kg and 10 kg, 8.1% high at 30 kg and 16.8% high at 45 kg [1] [2].

The same percentages carry through to daily needs, because both are multiplied by the same 1.6 for a neutered adult [2]. This drift happens because the shortcut is a straight line while the requirement rises on a curve (weight to the 0.75 power) [2].

Why calorie needs scale by weight to the 0.75 power

Calorie needs do not increase in direct proportion to body weight. Our own calculations (2026-11-08) show that as dogs get bigger, their energy requirement rises more slowly than their weight does: a dog ten times heavier needs about 5.6 times the resting energy, not ten times, because the formula uses body weight to the 0.75 power [1]. This is why the shortcut, which just multiplies weight by 30 and adds 70, starts to mislead at the extremes—it matches the curve of real needs only in the middle range. That is why MSD limits the shortcut to animals over 2 kg and under 45 kg [3].

From resting energy to daily needs: the multipliers

The formula above gives the daily needs for a neutered, healthy adult. The base, called Resting Energy Requirement (RER), is 70 × (weight in kg)^0.75 [1,3]. Multipliers adjust this for life stage and neuter status:

• Neutered adult: 1.6 × RER [3]
• Intact adult: 1.8 × RER [3]
• Obesity-prone: 1.4 × RER [3]
• Puppy (to 4 months): 3 × RER [3]
• Puppy (over 4 months): 2 × RER [3]

Example: For a 20 kg neutered dog, RER is 662 kcal (70 × 20^0.75), so daily need is 1.6 × 662 = 1059 kcal [1].

These are starting points—monitor your dog's body condition and adjust as needed [1,3].

A worked example: calculating calories for your dog

Suppose you have a neutered adult dog weighing 20 kg (about 44 lb; divide pounds by 2.2 for kilograms).

1. Calculate weight to the 0.75 power: 20^0.75 = 9.46 [1]
2. Multiply by 70 to get RER: 9.46 × 70 = 662 kcal [1]
3. Multiply by 1.6 (neutered adult): 662 × 1.6 = 1059 kcal per day [1]

If you feed a kibble with 350 kcal per cup (check your food bag), that is 1059 ÷ 350 ≈ 3 cups per day.

Why every figure is a starting point: adjust by body condition

MSD notes that every calorie calculation is only a starting point, to be adjusted by how the animal responds [3]. The real check is your dog's body condition, not the calories on paper. Weigh your dog and look at its shape over the following weeks; if it gains or loses, change the amount a little at a time, and ask your vet before a big change.

Questions readers ask

What about puppies, pregnant, or nursing dogs?

Puppies need much more: three times RER up to 4 months, two times RER after [3]. Pregnant or nursing dogs have higher requirements not covered by the formulas above—ask your vet for specifics [1,3].

Does breed or activity level change the formula?

Yes. The daily figure assumes a moderately active dog [3]; for a dog much more or less active, start from it and adjust by how its weight changes.

How the numbers work

Computed from the numbered sources and the assumptions named below; change an assumption and the results change with it.

*Corrected 2026-11-08: The title no longer promises accuracy: the page itself says every figure is a starting point to adjust by body condition. Pounds-to-kilograms conversion added for the worked example. Repeated warning, tip, reminder and checklist boxes and a generic feeder question were removed; the figures and the MSD multipliers were rechecked and stand. Headline was: "Calculate your dog's daily calorie needs accurately".*

*Corrected 2026-11-08: The combined formula is now shown as the combination of MSD's two published steps, not as a single MSD line.*

Sources

1. Our own calculation (2026-11-08): a dog's daily calories, exact formula against the shortcut
2. Our own calculation (2026-11-08): resting calories by weight, exact formula and shortcut, 2 to 45 kg, two ways
3. Nutritional Requirements of Small Animals - Management and Nutrition - MSD Veterinary Manual
4. Companion Animal Nutrition Support Service | Veterinary Medical Center