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How To Calculate How Much Food to Feed your Dog or Cat

By Dr. Andrew Jones

dog cat feeding

Doc..How Much Do I Feed?

One of THE most common veterinary questions.

Many different opinions, many different experts suggesting a range of amounts.

The most reliable approach is to feed the amount that maintains your dog or cat at an appropriate body weight. Your pet should have a loose covering over their ribs.

There are a variety of calculators etc, but I’ll give you some great guidelines.

First a ‘rough’ guide is approximately 1 cup of dry dog food/20 lbs of your dog’s weight daily.

Meaning for my 40lb dog Jessie, he gets 2 cups total- 1 cup in the morning, and 1 cup in the evening.

You can use this Body Condition Chart to determine if your pet is at the correct weight: (courtesy of Purina)

Too Thin


1. Ribs, lumbar vertebrae, pelvic bones and all bony prominences evident from a distance. No discernible body fat. Obvious loss of muscle mass.

2. Ribs, lumbar vertebrae and pelvic bones easily visible. No palpable fat. Some evidence of other bony prominence. Minimal loss of muscle mass.

3. Ribs easily palpated and may be visible with no palpable fat. Tops of lumbar vertebrae visible. Pelvic bones becoming prominent. Obvious waist.



4. Ribs easily palpable, with minimal fat covering. Waist easily noted, viewed from above. Abdominal tuck evident.

5. Ribs palpable without excess fat covering. Waist observed behind ribs when viewed from above. Abdomen tucked up when viewed.

Too Heavy


6. Ribs palpable with slight excess fat covering. Waist is discernible viewed from above but is not prominent. Abdominal tuck apparent.

7. Ribs palpable with difficulty; heavy fat cover. Noticeable fat deposits over lumbar area and base of tail. Waist absent or barely visible. Abdominal tuck may be present.

8. Ribs not palpable under very heavy fat cover, or palpable only with significant pressure. Heavy fat deposits over lumbar area and base of tail. Waist absent. No abdominal tuck. Obvious abdominal distension may be present.

9. Massive fat deposits over thorax, spine and base of tail. Waist and abdominal tuck absent. Fat deposits on neck and limbs. Obvious abdominal distention.

If you’re using a commercial pet food, just be careful of using the“feeding guidelines” on the bag.

Many pets are overweight as the directions on the label suggest portion sizes that are too large.

Start at the low end of the feeding guidelines.

Exactly Calculating How Much To Feed

Here’s How You can get an EXACT amount..

First we have to figure out your pet’s energy requirements.

RER stands for Resting Energy Requirement.

The RER is the basic amount of energy that your pet would use in a
day while remaining at rest. The formula to calculate RER for animals
between 2 and 45 kg (5 – 99 pounds) is:

RER in kcal/day = 30(body weight in kilograms) + 70

Any activity or variable other than rest will require an increase in
energy (RER) and an increase in calories to meet the energy needs.

Realize that these numbers are not a reflection of maintenance calories
but of resting energy levels.

Here are some calculations for energy requirements.

Weight Loss..1.0RER
Normally Active 1.5RER
Puppy and Kitten 0-4 months 3.0RER
Puppy and Kitten 4 months-Adult 2.0RER
Pregnat Female First 4 weeks 2.0RER
Pregnant Female Last 4 weeks 3.0RER
Lactating Female 5.0RER
So is that NOT as CLEAR as mud????????????
So to break this down into the real world.


An average dog ie Lewis consumes approx 1 cup of dry quality
dog food per 20lbs of body weight. He weighs 93lbs
or around 40kg.

He eats 5 cups a day.

Lewis’s RER is his body weight 40kg*30= 1200+70= 1270

Lewis’s Maintenance energy requirement is 1.5 * 1270 which is
1900 kcal/day.

Lewis’s dog food has 400 kcal/cup.

Therefore Lewis should be consuming 5 cups a day.

Best Wishes,

Andrew Jones, DVM

P.S. You should also be aware of exactly WHAT is a quality pet food, and what is NOT.

I have published my Advised Pet Food List here:



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Topics: Cat Care, Dog Care, Pet Care | No Comments »


Dr. Andrew Jones, DVM