Two dogs of the same weight can need meaningfully different amounts of food. One is neutered, sleeps most of the day and lives in a flat. The other is intact, walks twice daily and patrols a compound.
The feeding guide on the bag treats them identically. It also happens to be published by the company selling the food.
So here is how to work it out yourself, and, more importantly, how to tell whether you got it right.
The calculation
Step 1: resting energy requirement.
RER (kcal/day) = 70 × (body weight in kg)0.75
This is what your dog burns doing nothing at all.
Step 2: multiply for real life.
| Dog | Multiplier |
|---|---|
| Neutered adult, typical activity | × 1.6 |
| Intact adult | × 1.8 |
| Very active / working | × 2.0-5.0 |
| Overweight, on a weight-loss plan | × 1.0 (of target weight) |
| Senior, less active | × 1.4-1.6 |
Step 3: use the table.
| Weight | RER | Neutered adult (×1.6) | Intact adult (×1.8) |
|---|---|---|---|
| 5 kg | 234 | 374 kcal | 421 kcal |
| 10 kg | 394 | 630 kcal | 709 kcal |
| 15 kg | 534 | 854 kcal | 960 kcal |
| 20 kg | 662 | 1,059 kcal | 1,192 kcal |
| 25 kg | 783 | 1,252 kcal | 1,409 kcal |
| 30 kg | 897 | 1,436 kcal | 1,615 kcal |
| 40 kg | 1,113 | 1,781 kcal | 2,004 kcal |
Step 4: convert to a portion. Find the kcal per 100 g on your food's label. Across brands this ranges from roughly 330 to 420 kcal per 100 g, enough variation that ignoring it makes the whole exercise pointless. Divide the daily target by the food's kcal per gram.
Step 5: subtract treats. Treats, chews, training rewards and the biscuit from the neighbour should total no more than 10% of the daily calories, and they come out of the total rather than sitting on top of it. This is where most careful feeding plans quietly fail.
Now stop trusting the number
That calculation is a hypothesis. Your dog is the experiment.
Individual metabolism varies enough that two dogs of the same weight, age and neuter status can differ by 20% or more in what they actually need. The formula gets you to the right neighbourhood. Body condition tells you the address.
Body condition score: the skill worth learning
The 1-to-9 scale recommended by the WSAVA Global Nutrition Panel is the most extensively validated way to assess this:
| Score | Means | Roughly |
|---|---|---|
| 1-3 | Underweight | Ribs, spine and hip bones visible from a distance |
| 4-5 | Ideal | ~15-24% body fat |
| 6-7 | Overweight | ~25-34% body fat |
| 8-9 | Obese | ≥35% body fat |
How to score your dog, three checks, thirty seconds, weekly:
- Ribs. Run your fingers flat along the ribcage. At an ideal score you feel them easily under a thin covering, without pressing. If you have to push to find them, your dog is carrying too much. If they are sharp and visible across the room, too little.
- From above. Look down at a standing dog. There should be a visible waist behind the ribcage. A straight line, or an outward bulge, means overweight.
- From the side. The abdomen should tuck upward from the ribcage toward the hind legs. A belly running straight back, or sagging, means overweight.
Do this weekly, at the same time, ideally with the same hands. The trend is what matters, dogs change slowly and you will miss it by eye alone.
Adjusting
Change by 10% at a time, then wait three to four weeks. Reacting faster than that means reacting to noise.
For weight loss: target roughly 1 to 2% of body weight per week. Faster is not better, rapid loss costs muscle alongside fat. Feeding at approximately RER for the target weight is a common starting point.
Do this with a vet. Not as a formality: a dog that gains weight on a reasonable diet may have hypothyroidism or Cushing's, and dieting a dog with an untreated endocrine disease is treating a symptom.
For weight gain, the priority is finding out why first. A dog losing weight on adequate food has a medical problem until proven otherwise, parasites, malabsorption, dental pain, kidney disease, diabetes.
Practical things that change the answer
Two meals a day, not free-feeding. Free access makes the intake unmeasurable, and unmeasurable intake cannot be adjusted.
Weigh the food. A measuring cup is off by a surprising margin between fillings; kitchen scales cost very little and remove the variable entirely.
Neutering lowers requirements by a meaningful amount, and the weight gain that follows is usually a feeding failure rather than an inevitability. Recalculate at the time of the surgery rather than three kilos later.
Everyone in the household counts. The most common reason a carefully calculated plan does not work is a second person feeding a second dinner. Agree it once, out loud.
Indian street-fed dogs eat what the neighbourhood provides on top of what you give. If your dog roams, your portion is a contribution, not the total, and body condition is the only measure that captures the truth.
The bottom line
Calculate the starting point from the formula, not the bag. Convert honestly using the label's kcal figure. Take treats out of the total.
Then put the calculator away and learn to read the dog: ribs under the fingers, waist from above, tuck from the side, weekly.
The arithmetic gets you close. Your hands get you right.
Feeding a growing puppy is a different calculation with different multipliers, see the puppy feeding chart.