Resting Energy Requirement (RER) is the foundation of every veterinary feeding recommendation. It tells you how many calories your dog needs just to stay alive at complete rest — before any activity, growth, or recovery is considered. Understanding RER is the first step to accurate feeding.
The RER Formula Explained
RER = 70 × (kg)0.75
Where kg = body weight in kilograms (1 lb = 0.4536 kg)
Why the 0.75 Exponent? The Science of Metabolic Scaling
The exponent 0.75 comes from Kleiber's Law (1932), one of the most well-established principles in biology. Max Kleiber discovered that metabolic rate across mammals scales with body mass raised to the power of ¾ — not linearly.
This means energy needs don't double when weight doubles. A 40 kg dog doesn't need twice the calories of a 20 kg dog — it needs about 1.68× as much. The relationship is sublinear because larger bodies are more metabolically efficient per kilogram.
The constant 70 was derived from studies measuring oxygen consumption in dogs under basal metabolic conditions. Together, 70 × kg0.75 produces remarkably consistent predictions across the full range of dog sizes, from a 2 kg Toy Poodle to a 80 kg English Mastiff.
Why RER Is Not Your Dog's Daily Feeding Amount
RER represents only the energy cost of basic survival: breathing, circulation, maintaining body temperature, and cellular processes. It does not include:
- Physical activity (walking, playing, running)
- Thermoregulation in cold weather
- Growth (puppies)
- Reproduction (pregnancy/lactation)
- Recovery from illness or surgery
- Digestion of food itself (thermic effect)
That's why veterinary nutritionists multiply RER by life-stage factors to arrive at MER (Maintenance Energy Requirement). For a complete breakdown of MER multipliers, see our Complete Dog Calorie Guide.
5 Weight-Based RER Examples
| Dog Size | Weight | kg0.75 | RER (kcal) |
|---|---|---|---|
| Chihuahua (5 kg) | 5 kg / 11 lbs | 3.34 | 234 kcal |
| Beagle (10 kg) | 10 kg / 22 lbs | 5.62 | 394 kcal |
| Border Collie (20 kg) | 20 kg / 44 lbs | 9.46 | 662 kcal |
| Labrador Retriever (30 kg) | 30 kg / 66 lbs | 12.82 | 897 kcal |
| German Shepherd (50 kg) | 50 kg / 110 lbs | 18.80 | 1316 kcal |
Notice how a 50 kg dog's RER (1316 kcal) is not 10× a 5 kg dog's RER (234 kcal) — it's only 5.6× thanks to metabolic scaling.
Get Your Dog's Full Calorie Calculation
Our Dog Calorie Calculator applies RER + life-stage multipliers automatically. Enter weight and get instant results.
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Important Disclaimer
RER provides a scientifically validated baseline estimate. Individual metabolism varies by ±20%. Always monitor body condition over time and adjust feeding accordingly. Dogs with health conditions require veterinary guidance for dietary planning.