RER Calculator for Dogs: Formula and Chart

What RER Means for Your Dog

RER stands for Resting Energy Requirement. It's the number of calories your dog burns just to stay alive while lying still in a comfortable room: breathing, pumping blood, digesting, keeping organs running.

Vets and veterinary nutritionists use RER as the starting point for almost every feeding plan. It doesn't account for walks, play, growth, or pregnancy. Those get layered on top with a multiplier, which we'll cover below.

If you want the broader picture of daily calories, our dog calorie calculator guide walks through the whole process. This post zooms in on the RER step itself, so you can do the math confidently and check any online calculator's answer.

What You'll Need

• Your dog's weight, ideally from a recent vet visit or a bathroom-scale weigh-in
• A phone calculator with an exponent key (x^y), or the square-root trick below
• A rough idea of your dog's life stage: puppy, neutered adult, intact adult, or a dog that needs to slim down

Step 1: Convert Your Dog's Weight to Kilograms

The formula only works in kilograms. Divide your dog's weight in pounds by 2.2046.

A 40 lb dog weighs 40 ÷ 2.2046 = 18.14 kg. Keep a couple of decimal places here; rounding too early can shift the final answer by several calories.

Step 2: Apply the RER Formula

The standard formula, listed in the Merck Veterinary Manual, is:

RER (kcal/day) = 70 × (body weight in kg)^0.75

For our 40 lb dog, 18.14^0.75 = 8.79, and 70 × 8.79 = about 615 kcal per day.

No exponent key? Today's Veterinary Nurse describes an equivalent shortcut. Multiply the weight by itself three times, press the square-root button twice, then multiply by 70. For a 10 kg dog, that's 10 × 10 × 10 = 1,000, then √ twice gives 5.62, and 5.62 × 70 = about 394 kcal.

Why the 0.75 exponent?

Bigger animals burn fewer calories per kilogram than small ones. The Pet Nutrition Alliance explains that RER tracks metabolic body size, which relates to body surface area rather than raw weight. That's why a 100 lb dog doesn't need ten times the calories of a 10 lb dog. In the chart below, it needs about 5.6 times as much.

What about the linear formula?

You may also see RER = (30 × kg) + 70. Merck notes this shortcut only applies to dogs heavier than 2 kg and lighter than 45 kg. The exponential version works at any size, so it's the one we use here.

RER Chart by Weight

These numbers use the exponential formula. Weights were converted at 2.2046 lb per kg, kilograms are shown rounded to one decimal, and RER was calculated from the unrounded kilogram value, then rounded to the nearest whole Calorie.

If your dog falls between rows, run the formula directly rather than averaging two rows. The curve isn't a straight line, so averaging slightly overestimates.

Step 3: Turn RER Into Daily Calories (MER)

Your dog's actual daily need is called the Maintenance Energy Requirement (MER), sometimes called Daily Energy Requirement (DER). You get it by multiplying RER by a factor. The Pet Nutrition Alliance's calorie guide lists these canine factors:

Merck splits puppies further: about 3 × RER under 4 months old and 2 × RER after that.

So our 40 lb neutered adult would start around 615 × 1.6 = 984 kcal per day. The same dog, intact, would start near 1,107 kcal.

For puppy-specific portions, see our puppy feeding chart. To convert calories into cups of a specific food, our guide on how much food you should feed your dog shows how to read the kcal per cup on the bag.

Step 4: Watch Your Dog, Then Adjust

Every formula is a starting point, not a prescription. The Pet Nutrition Alliance warns that individual dogs can vary by as much as 50% from predicted values. Merck puts the swing at about 30% between dogs of the same weight.

Feed your calculated amount for two to three weeks, then check:

1. Weigh your dog on the same scale at the same time of day.
2. Feel the ribs. You should find them easily under a thin layer of fat, without pressing hard.
3. Adjust by about 10% up or down if weight is drifting the wrong way, then recheck in another few weeks.

Ohio State's Veterinary Medical Center calorie calculator page makes the same point: treat the number as an estimate and fine-tune from your dog's body condition.

Common Mistakes to Avoid

• Forgetting to convert to kilograms. Plugging pounds into the formula inflates the answer by roughly 80%.
• Feeding RER alone to a healthy adult. RER is a resting number. Most active, healthy dogs need more than that.
• Using current weight for an overweight dog. For weight loss, vets usually base RER on the target weight. Get your vet involved before cutting calories hard.
• Ignoring treats. Chews, training rewards, and table scraps all count toward the daily total.
• Skipping the recheck. A number you never revisit can quietly add pounds over a year.

Tips for Different Dogs

Toy and small breeds. A 10 lb dog's RER is only about 218 kcal, so a single heavy treat can be a big slice of the day. Our small breed dog food guide covers calorie-dense options.

Large and giant breeds. RER climbs more slowly than weight, so big dogs often need less than owners expect. Large-breed puppies in particular shouldn't be pushed to grow too fast.

Seniors. Older dogs often move less, so many land closer to the inactive range. Weigh them more often.

Dogs losing weight unexpectedly. If your dog is dropping pounds and you haven't changed the food, the math isn't the issue. Read our guide on why a dog might be losing weight and call your vet.