"Feed two cups a day" only works if you know how many calories are in a cup — and
every food is different. The reliable way is to start from your dog's daily calorie
need and divide by your food's calories per cup. Enter your dog's weight, life stage,
and the kcal-per-cup from your bag below to get daily calories and cups per day.
Everything here follows the standard veterinary RER/MER energy-requirement method.
Calories first, then cups·8 life-stage & activity factors·Standard RER/MER formula
Read this first
This is an estimate from the standard RER/MER formula, not veterinary advice. Your dog's
real needs depend on body condition score, breed, metabolism, spay/neuter status, and
health conditions, and no calculator is exact. Confirm the amount with your veterinarian
and follow your food's feeding guide.
Enter your dog's weight, pick the life stage or activity level that fits, and enter your food's calories per cup (printed on the bag as "ME kcal/cup"). You'll get daily calories and cups per day.
Use your dog's current weight — or target weight if feeding for weight loss.
The factor multiplies resting energy to reach the daily total.
Default 350. Find the exact "ME kcal/cup" on your food's bag or the maker's site. Dry foods often run 300–500.
Daily calories (MER)
Cups per day
Resting energy (RER)
Activity factor
Per meal (twice daily)
The math, honestly
How the calculation works (RER & MER)
Vets don't start from cups — they start from calories. The first
number is the resting energy requirement (RER): the energy a dog burns at rest. It
scales with body weight in kilograms, raised to the three-quarter power, because
smaller animals burn more energy per pound than larger ones.
RER = 70 × (weight in kg)0.75
Then RER is multiplied by an activity factor for the dog's life
stage and lifestyle to get the maintenance energy requirement (MER) — the daily
calorie target. A typical neutered adult uses about 1.6; a growing puppy or a working
dog can need up to 3.0.
MER (daily calories) = RER × activity factor
Finally, divide daily calories by your food's calories per cup to
translate calories into a real serving. Two foods with the same dog can require very
different cup amounts, which is why a fixed "two cups" rule of thumb so often misses.
cups per day = daily calories ÷ kcal per cup
Worked example: a 44 lb (about 20 kg) neutered adult. RER = 70 ×
200.75 ≈ 662 calories; MER = 662 × 1.6 ≈ 1,059 calories a
day; on a food with 350 calories per cup that's about 3 cups per day,
usually split into two meals.
Life-stage & activity factors
The activity factor is the multiplier applied to resting energy. These are the standard
published values used in small-animal nutrition. Pick the one that best matches your
dog; when two seem to fit, start lower and adjust by body condition.
Life stage / activity
Factor× resting energy
Notes
Weight loss
1.0
Calculate at the dog's target weight, not current.
Weight gain
1.4
Underweight dogs needing to put on condition.
Senior
1.4
Older, often less active adults.
Neutered adult
1.6
The most common everyday case.
Intact adult
1.8
Slightly higher needs than neutered.
Puppy, 4 mo–adult
2.0
Still growing, past the early sprint.
Active / working
3.0
High daily exercise or working dogs.
Puppy, 0–4 mo
3.0
Fastest growth; portions change often.
Factors are standard published multipliers and represent typical cases. Individual dogs
vary with metabolism, breed, and health, so treat the result as a starting estimate and
tune it to your dog's body condition with your veterinarian.
Example daily calories by weight
Daily calories (MER) and cups per day for a typical neutered adult
(factor 1.6) at a few weights, assuming a food with 350 calories per cup. Find a weight
close to your dog's, but use the calculator above for your dog's actual numbers.
Weight
Resting energyRER, kcal
Daily caloriesMER, ×1.6
Cups per dayat 350 kcal/cup
10 lb · 4.5 kg
218
348
1.0
20 lb · 9.1 kg
366
585
1.7
30 lb · 13.6 kg
496
794
2.3
44 lb · 20.0 kg
662
1,059
3.0
60 lb · 27.2 kg
834
1,334
3.8
75 lb · 34.0 kg
986
1,578
4.5
90 lb · 40.8 kg
1,131
1,809
5.2
Calories are rounded to whole numbers and cups to one decimal. These assume a neutered
adult on a 350 kcal/cup food; a denser food means fewer cups and a lighter food means
more, so always read your own bag's calories-per-cup figure.
The three steps, in plain terms
The whole method comes down to three moves: find resting energy, scale it for the dog,
then convert calories into cups using your food.
Step 1
Resting energy
Convert weight to kilograms and compute RER = 70 × kg0.75. This is the baseline energy a dog burns just existing, before any activity.
Step 2
Scale for the dog
Multiply RER by the activity factor for the life stage and lifestyle — 1.6 for a neutered adult, up to 3.0 for a puppy or working dog — to get daily calories (MER).
Step 3
Calories to cups
Divide daily calories by your food's calories per cup. Split the total across the meals you feed — most dogs do well on two meals a day.
Then
Tune by condition
Re-check against body condition score: ribs easy to feel, a visible waist from above. Adjust the amount up or down and confirm with your veterinarian.
Where to buy
Got your numbers? Here's where to pick up what you need:
The terms behind the calculator, in plain English. Definitions reflect standard
small-animal nutrition usage — they are background, not advice.
Resting energy requirement (RER)
The calories a dog needs at complete rest, in a comfortable environment, neither growing nor exercising. Calculated as 70 × body weight in kilograms to the 0.75 power. RER is the foundation every other feeding number is built on.
Maintenance energy requirement (MER)
The full daily calorie need once activity, life stage, and lifestyle are accounted for. It equals RER multiplied by an activity factor. MER is the number you actually feed to.
Activity factor
A multiplier applied to resting energy to reflect how much more than rest a dog needs — for example about 1.6 for a neutered adult, 2.0 for a growing puppy, or up to 3.0 for a working dog. These are standard published values, not exact measurements for any individual dog.
Calories per cup (ME kcal/cup)
The metabolizable energy in one cup of a specific food, printed on the bag. Because foods differ widely — roughly 300 to 500 calories per cup for many dry foods — the same dog needs a different number of cups depending on the food. Always use your own bag's figure.
Body condition score (BCS)
A hands-on assessment of whether a dog is at a healthy weight, usually on a 1–9 scale where about 4–5 is ideal. You should be able to feel the ribs easily without pressing, and see a waist from above. BCS is the practical check that tells you whether the calculated amount is actually right.
Metabolizable energy (ME)
The energy in a food that a dog can actually absorb and use, after losses in feces and urine. It is the basis for the calories-per-cup figure on pet food labels and the number this calculator divides into the daily calorie target.
Spay / neuter status
Whether a dog has been surgically sterilized. Neutered and spayed dogs tend to have slightly lower energy needs, which is why the neutered-adult factor (about 1.6) is a bit below the intact-adult factor (about 1.8).
Senior dog
An older dog, often less active, frequently fed at a factor around 1.4. The age at which a dog is "senior" varies with size, and some seniors with health conditions need very different amounts — a reason to set feeding with a veterinarian.
Frequently asked
Start from your dog's daily calorie need, not a fixed cup amount. The standard veterinary method is to calculate resting energy (RER = 70 × body weight in kilograms to the 0.75 power), then multiply by an activity factor for your dog's life stage and lifestyle — about 1.6 for a typical neutered adult or 2.0 for a growing puppy. That gives daily calories (MER). Divide by your food's calories per cup to get cups per day. The calculator above does all of this. It's an estimate — confirm the amount with your veterinarian and follow your food's feeding guide.
Cups per day depends on two numbers: your dog's daily calorie need and how many calories are in one cup of your food. A 44 lb (about 20 kg) neutered adult needs roughly 1,060 calories a day, so on a food with 350 calories per cup that's about 3 cups daily, usually split into two meals. A more calorie-dense food means fewer cups; a lighter food means more. Always read the calories-per-cup figure off your own bag rather than assuming, because it varies a lot between products.
Three steps. First, find resting energy: RER = 70 × (weight in kg) to the power of 0.75. Second, multiply by an activity factor — common values are 1.6 for a neutered adult, 1.8 for an intact adult, 1.4 for a senior or weight gain, 1.0 for weight loss, 2.0 for a puppy past four months, and up to 3.0 for very active or working dogs and young puppies. That product is the daily maintenance energy requirement (MER) in calories. Third, divide daily calories by your food's calories per cup to get cups per day, then split that across the meals you feed.
Look on the bag or the manufacturer's website for a metabolizable energy figure, usually printed as "ME" and given as kcal per cup or kcal per kilogram. The kcal-per-cup number is the one this calculator uses. If your bag only lists kcal per kilogram of food, you'll need the cup weight to convert, so it's easiest to use the per-cup value. Dry foods commonly run from about 300 to 500 calories per cup, which is why two foods can require very different cup amounts for the same dog.
Puppies need far more energy per pound than adults because they're growing. Veterinary feeding factors are roughly 3.0 times resting energy for puppies up to about four months, then about 2.0 from four months until they reach adult size, compared with about 1.6 for a typical neutered adult. Because puppies grow quickly, their portions change often, so weigh regularly and adjust. Use a food formulated for growth or for all life stages, and confirm amounts with your veterinarian.
For weight loss, vets typically calculate resting energy at the dog's target (ideal) weight and apply a factor of about 1.0 — feeding for rest at the goal weight rather than the current weight. This calculator's "weight loss" option uses a factor of 1.0; enter your dog's target weight, not its current weight, to use it that way. Weight loss should be gradual and monitored, so a vet-guided plan with regular weigh-ins is strongly recommended rather than cutting food sharply on your own.
RER stands for resting energy requirement — the calories a dog needs at rest — and is calculated as RER = 70 × (body weight in kilograms) raised to the 0.75 power. MER stands for maintenance energy requirement and is the RER multiplied by an activity factor that reflects life stage and lifestyle. This is the established small-animal nutrition method. The activity factors are standard published multipliers, but every dog is different, so the result is a starting estimate to refine with your vet using body condition score.
Recheck the amount whenever your dog's weight, age, activity, or health changes, and otherwise every few weeks at first. The single best guide is body condition score: you should be able to feel the ribs easily without pressing hard, and see a waist from above. If your dog is gaining unwanted weight, reduce the amount; if losing or always hungry and underweight, increase it. The calculator gives a starting point — real intake should be tuned to the dog in front of you, ideally with your veterinarian.
Common mistakes with this calculator
Trusting the bag's feeding chart over a calorie-based calculation
Feeding guides printed on bags are intentionally generous — they're calibrated to average dogs and food companies benefit from higher usage. A neutered adult, a senior, or an overweight dog almost always needs less than the bag suggests. The RER/MER method (RER = 70 × kg0.75, per the Merck Veterinary Manual and WSAVA guidelines) starts from the dog's actual physiology. Use the bag chart as a rough sanity-check, not as the amount to feed.
Not reading the actual kcal/cup off the bag
Dry dog foods range from roughly 300 to 500 kcal/cup. Assuming a generic average — or using this calculator's default without checking — can over- or under-feed by 30% or more. The metabolizable energy (ME) is printed on every bag, typically as "ME kcal/cup" or "kcal/kg." If only kcal/kg is listed, divide by the grams-per-cup for your food to get kcal/cup.
Using the intact-adult factor for a neutered dog
Neutered and spayed dogs have meaningfully lower energy needs than intact adults. The standard factor is about 1.6 for a neutered dog versus 1.8 for an intact one. Feeding at the intact rate adds roughly 12% excess calories daily, which accumulates into steady weight gain — one of the most common and preventable causes of obesity in pet dogs.
Setting current weight instead of target weight for weight-loss mode
For weight loss, the established veterinary approach is to calculate RER at the dog's target ideal weight and multiply by about 1.0. If you enter the current heavier weight with a weight-loss factor, the calorie target comes out too high and the dog won't lose. Enter the goal weight, not current weight, when using the weight-loss setting — and confirm the plan with your veterinarian.