What does RER mean for dogs?

RER stands for Resting Energy Requirement — the number of calories your dog's body burns at complete rest, just maintaining basic body functions. It's the baseline that all other calorie recommendations, including your dog's actual feeding amount, are calculated from.

What is the RER formula for dogs?

The WSAVA-referenced formula is RER = 70 × (body weight in kg)^0.75. A simpler linear version (30 × kg + 70) is used sometimes but loses accuracy for very small or very large dogs.

Is RER the same as how many calories I should feed my dog?

No — RER is just the resting baseline. Your dog's actual feeding target, called DER (Daily Energy Requirement), is RER multiplied by an activity and life-stage factor, which is usually somewhere between 1.0 and 3.0 depending on the dog.

How do I calculate my dog's DER from RER?

Multiply RER by a factor matching your dog's situation: roughly 1.6 for a neutered adult, 1.8 for an intact adult, 1.0 for active weight loss, and 2.0-3.0 for growing puppies. Your vet can help pick the right multiplier if you're unsure.

Why does the RER formula use an exponent instead of just multiplying by weight?

Metabolic rate doesn't scale in a straight line with body weight — a dog twice as heavy doesn't burn exactly twice the calories at rest. The 0.75 exponent reflects that curve and keeps the formula accurate across both small and giant breeds.

Does RER change as my dog ages?

RER itself is based on current weight, so it changes only if your dog's weight changes. What typically shifts with age is the DER multiplier — senior dogs are usually less active and need a lower multiplier even if their RER stays similar.

Can I use RER for a puppy?

Yes, but puppies need a much higher DER multiplier than adult dogs — often 2.0 to 3.0 times RER — because growth itself burns significant energy on top of resting maintenance.

Is the linear RER formula (30 × kg + 70) accurate enough?

It's a reasonable shortcut for mid-sized dogs roughly between 2 and 45 kg, but it becomes noticeably less accurate for very small or very large dogs, where the exponential formula holds up better.

Dog RER Calculator: Resting Energy Requirement Formula (2026)

What RER Actually Means

RER stands for Resting Energy Requirement — the number of calories your dog's body burns just existing, lying on the couch, doing absolutely nothing productive. No walks, no zoomies, no begging at the counter. Just the baseline cost of keeping organs running, cells dividing, and body temperature steady.

It sounds like a niche vet-school number, but it isn't. Every calorie recommendation you've ever seen for a dog — the back of a kibble bag, a vet's handout, an app that tells you how many cups to feed — starts from RER and multiplies it by something. If you've ever wondered why two "calorie calculators" for the same size dog give you different answers, the difference usually isn't the RER math. It's what each one multiplies RER by afterward. So getting RER right first is worth five minutes of your attention.

The Formula Vets Actually Use

There are two versions floating around online, and only one of them holds up across the full range of dog sizes.

The simple linear formula — RER = 30 × weight in kg + 70 — is fine for dogs roughly in the 2-45 kg range, but it starts drifting the further you get from a medium-sized dog. For a Chihuahua or a Great Dane, it can be off by a meaningful margin.

The formula WSAVA (World Small Animal Veterinary Association) actually references, and the one used in veterinary nutrition textbooks, is exponential:

RER = 70 × (body weight in kg)^0.75

That 0.75 exponent is doing real work — it accounts for the fact that metabolic rate doesn't scale directly with body mass. A dog twice the weight of another doesn't burn exactly twice the calories at rest; metabolism scales a bit more slowly than that. This is why the exponential version is the one that stays accurate whether you're calculating for a 4-pound Yorkie or a 150-pound Mastiff.

RER by Weight: A Quick Reference Table

These figures use the exponential formula and are rounded to the nearest whole number. Your dog's exact RER depends on their precise weight, so treat this as a reference point rather than a substitute for punching in your dog's actual number — the RER Calculator does that instantly.

Dog's Weight	Weight in kg	RER (kcal/day)
10 lbs	4.5 kg	~218 kcal
20 lbs	9.1 kg	~366 kcal
30 lbs	13.6 kg	~496 kcal
40 lbs	18.1 kg	~615 kcal
50 lbs	22.7 kg	~727 kcal
60 lbs	27.2 kg	~834 kcal
70 lbs	31.8 kg	~937 kcal
80 lbs	36.3 kg	~1,035 kcal
90 lbs	40.8 kg	~1,131 kcal
100 lbs	45.4 kg	~1,224 kcal

Notice the curve flattens slightly as weight climbs — a 100-lb dog doesn't need 10x the calories of a 10-lb dog, it needs about 5.6x. That's the 0.75 exponent showing up in real numbers, and it's exactly the kind of math that's easy to get wrong doing it by hand.

RER Is Not the Number You Feed To

This is the part that trips people up: RER on its own is not a feeding target. It's the baseline your dog's actual calorie needs get built from, using something called DER — Daily Energy Requirement.

DER = RER × an activity/life-stage multiplier, and that multiplier swings hard depending on your dog:

Intact adult, moderate activity: RER × 1.8
Neutered/spayed adult, moderate activity: RER × 1.6
Weight loss: RER × 1.0
Weight gain needed: RER × 1.2-1.8
Puppy, under 4 months: RER × 3.0
Puppy, 4 months to adult: RER × 2.0
Senior, less active: RER × 1.2-1.4
Working or highly active dogs: RER × 2.0-5.0

So a neutered 50-lb adult dog isn't eating 727 kcal a day — they're eating closer to 727 × 1.6, or roughly 1,163 kcal. Skip this step and you'll either underfeed a working dog into a skeleton or overfeed a couch potato into obesity, all while thinking you did the math correctly.

Why This Formula Matters More Than People Realize

Vets lean on RER-based math instead of "cups per day" guidelines because kibble bag recommendations are built for the average dog eating that average food, and your dog is very likely not average in at least one way — activity level, spay/neuter status, breed-typical metabolism, or age. RER math adjusts for the individual animal in front of you rather than the mythical average dog on the packaging.

It's also the backbone of clinical nutrition. If your dog needs a prescription weight-loss diet, is recovering from surgery, or has a condition where calorie precision actually matters medically, your vet is running some version of this same calculation, often with additional adjustments layered on top for body condition score and specific health factors.

Common Mistakes People Make With RER

Using the wrong weight. RER should be calculated from a dog's current healthy or target weight, not their aspirational weight and not last year's weight. If your dog has gained or lost a noticeable amount, recalculate — and if you're not sure whether your dog's current weight is actually a healthy starting point, check their body condition score first, since a dog technically "in range" on a chart can still be carrying extra fat for their frame.

Forgetting the DER step entirely. Calculating RER and then feeding that number directly is probably the single most common error — it usually results in significant underfeeding, since DER multipliers are almost always greater than 1.0 for anything other than active weight loss.

Using the linear formula for small or giant breeds. The 30x+70 shortcut is convenient but the error margin grows meaningfully at the extremes. If your dog is under 5 lbs or over 100 lbs, the exponential formula is worth the extra effort.

Treating the multiplier as fixed. Activity level changes — a dog recovering from an injury needs a lower multiplier temporarily, a dog training for agility needs a higher one. RER stays roughly the same for a given weight; DER is the number that should move with your dog's actual life.

Putting It Together

Start with your dog's current weight in kilograms. Run it through the exponential formula, or skip the arithmetic and use the RER Calculator, which does the 0.75 exponent instantly and won't round the way a mental estimate does. From there, apply the DER multiplier that matches your dog's life stage, activity, and spay/neuter status — and if you're not sure which multiplier fits, that's a reasonable thing to ask your vet at the next checkup rather than guessing.

Recommended Tools

RER / Kcal Calculator (vet-advanced mode) — Get the exact RER for your dog's current weight using the WSAVA-referenced formula.
Dog Calorie Calculator — Goes a step further and applies the DER multiplier for you automatically.
Dog Food Calculator — Converts your dog's daily calorie target into actual cups or grams of food.
Dog Weight Calculator — Confirm your dog is at a healthy starting weight before calculating calorie needs from it.
Dog Protein Calculator — Once calories are dialed in, check whether protein intake matches your dog's life stage too.

Start With the Number That Everything Else Is Built On

RER is the foundation, not the finish line — get it right, apply the correct multiplier for your dog's real life, and every other feeding decision gets easier from there.

→ Calculate Your Dog's RER Now