Dog Food Portion Calculator

The Resting Energy Requirement (RER) is the number of kilocalories a dog burns just keeping the lights on at rest: cardiac, respiratory, neural, and core metabolic function. The formula RER = 70 * (body weight in kilograms)^0.75 is the AAHA, WSAVA, and AAFCO accepted equation across pet nutrition. The 0.75 exponent (metabolic body weight) reflects that smaller animals burn more calories per pound than larger ones, since heat loss scales with surface area rather than mass. A 10 kg dog has an RER of roughly 394 kcal/day, a 30 kg dog roughly 898 kcal/day. Maintenance (MER) is RER multiplied by an activity factor.

Puppies are building bone, muscle, organs, and brain tissue at a rapid clip, and growth costs calories on top of normal maintenance. AAHA guidelines set puppy energy needs at roughly 2x RER for the first 4 months and around 1.6x RER from 4 months until they reach adult size, compared with 1.0 to 1.6x for adults. Puppies also have smaller stomachs, so the calculator splits their daily portion into 3 meals (4 meals is sensible under 4 months old) to keep blood sugar stable and prevent gastric overload. Free-feeding a puppy or skipping meals usually results in either rapid weight gain or hypoglycemia in toy breeds.

The activity multipliers follow AAHA Nutritional Assessment Guidelines for Dogs and Cats: sedentary (1.0x RER, indoor dog with short leash walks), moderate (1.4x, the typical pet dog with 1 to 2 hours of daily walks), active (1.6x, long hikes or off-leash runs daily), and working (2.0 to 5.0x for herding, sled, hunting, or sport dogs during active seasons). This calculator uses 2.5x as the midpoint for the working tier, since the high end of that range applies mostly to Iditarod sled dogs and similar extreme cases. Bump it up if your dog is doing real competition or field work and losing weight at 2.5x.

Spaying or neutering removes the sex hormones that drive basal metabolic rate and roaming behavior, and studies (Jeusette 2004, Larsen 2015) consistently show a 20 to 30 percent drop in resting metabolic needs after the procedure, partly offset by lower activity. AAHA guidelines recommend cutting daily intake by about 5 to 10 percent immediately after the surgery to avoid weight gain in the months that follow. This calculator applies a conservative 5 percent reduction (0.95x multiplier) when you check the spay/neuter box. Recheck body condition every 2 to 4 weeks for the first six months post-surgery and tighten further if you see weight creep.

Use the 9-point Body Condition Score (BCS) chart from WSAVA. Ideal is a 4 or 5 of 9, which translates to three visual checks: you can feel the ribs easily through a thin layer of fat without pressing hard, you can see an obvious waist when looking down from above, and you can see a tucked abdomen from the side. If you have to dig through fat to find ribs, the dog is overweight (BCS 6 to 7) and portions should drop by about 20 percent. If ribs, spine, and hip bones are visible without effort, the dog is underweight (BCS 2 to 3) and portions should rise by 20 percent. Reassess every 2 weeks and adjust again.