Pet Food Calculator
Estimate your pet’s daily food needs using weight, age, activity level and food information.
This calculator provides an estimate for general informational purposes and is not a substitute for veterinary advice.
Select pet type
Pet information
Food information
Calorie density varies a lot between brands and between dry and wet food. Two products at the same weight can supply very different energy, so read the panel on your own packaging — it is usually printed as kcal or ME per 100 g.
Your estimate
Estimate only
- Estimated daily food
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- Estimated daily energy
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- Meals per day
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- Approx. amount per meal
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- Approx. cups per day
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How the Pet Food Calculator works
Nothing is hidden. Here is the whole chain from the weight you type to the grams shown in the result.
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STAGE 01
Pet weight is entered
Weight is converted to kilograms first, because every published feeding formula is written in metric. If you enter pounds, the tool multiplies by 0.4536 before anything else happens.
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STAGE 02
Basic energy needs are estimated
For dogs and cats the tool uses resting energy requirement, or RER, calculated as 70 × body weight in kg raised to the power 0.75. This is the standard allometric equation used in small-animal nutrition. Rabbits, birds and small rodents use separate species-specific estimates instead, because that same equation was not written for them.
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STAGE 03
Age and activity modify the estimate
RER is multiplied by a life-stage factor (a growing puppy needs far more energy per kilogram than a senior dog) and then by an activity modifier. The combined result is the maintenance energy requirement, or MER, in kcal per day.
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STAGE 04
Food calorie density converts calories into grams
Daily kcal is divided by the calorie density of your specific food. At 360 kcal per 100 g, one gram supplies 3.6 kcal, so 700 kcal per day works out at roughly 194 g. Change the food and the gram figure changes even though the calorie figure does not.
Example: a 12 kg adult dog on dry food
This is an illustration of the arithmetic only. It is not feeding guidance for any particular animal, and a real dog of this weight may need noticeably more or less.
- Body weight → 12 kg
- RER → 70 × 12^0.75 = 70 × 6.45 = 451 kcal/day
- Life stage → adult, factor 1.6
- Activity → normal, modifier 1.00
- MER → 451 × 1.6 × 1.00 = 722 kcal/day
- Food → 360 kcal per 100 g = 3.6 kcal per gram
- Daily amount → 722 ÷ 3.6 = 201 g/day
- Split over 2 meals → 100 g per meal
Using the estimate day to day
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Check the food label
The manufacturer prints the calorie content and its own feeding chart. That chart is specific to that product, so read it alongside any calculator result.
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Measure portions accurately
A kitchen scale is more reliable than a scoop, because the same cup of kibble can vary in weight depending on the shape and density of the pieces.
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Divide daily food into meals
Split the daily total rather than adding meals on top of it. Treats also carry calories and come out of the same daily budget.
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Monitor body condition
Weigh your pet regularly and watch how their body shape changes over several weeks. Steady, unplanned weight change is the signal that the amount needs revisiting.
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Adjust with professional guidance
Pregnancy, illness, recovery from surgery, prescription diets and planned weight loss all change requirements in ways a general calculator cannot model. Those belong with a veterinarian.
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Change amounts gradually
If the estimate differs a lot from what you feed now, move towards it over several days rather than switching in one step.
Important — please read
Every pet is different. Nutritional requirements can vary because of breed, age, activity, body condition, health status, reproductive status and the specific food being fed. This calculator provides a general estimate only. Always follow the feeding guidance on the food label and consult a veterinarian for pets with medical conditions, unusual weight changes or special dietary requirements.
Pet food calculator FAQ
It estimates daily energy needs from body weight, then adjusts that figure for life stage and activity level, then converts the calories into a weight of food using the calorie density of the product you feed. Each of those four steps is shown in the method section above, so you can check the arithmetic yourself.
There is no single answer, because it depends on the species, the individual animal and the food. Enter your pet’s details above to get a starting figure, then compare it with the feeding chart on your food packaging. If the two are far apart, recheck your inputs before changing anything.
Yes, it is the largest single factor. Energy needs scale with body size, which is why the formula raises weight to the power 0.75 rather than using it directly. A doubling of body weight does not double the food requirement. Update the weight after a check-up and run the calculator again.
It does. An animal that rests most of the day burns less than one that works, runs or plays for long stretches. The calculator applies a modifier of 0.85 for low, 1.00 for normal, 1.15 for active and 1.35 for very active on top of the life-stage factor.
Young growing animals are usually fed more often than adults because they need more energy relative to their stomach capacity. The tool suggests four meals for very young pets, three during later growth and two for adults, and you can change that to fit your routine. What matters is that the daily total stays the same however you divide it.
Grams, if you have a kitchen scale. A cup is a volume measure, so the weight of kibble it holds changes with the size, shape and density of the pieces. The calculator shows cups only when you enter a calories-per-cup figure from your own packaging, because that number is product-specific.
Label charts are usually built around broad weight bands and assume an average adult at a typical activity level, so they cannot account for your particular pet as closely. They are also written for that exact recipe. Differences of ten or twenty per cent between a label chart and a calculator are common and do not mean either one is wrong.
You can select a growth life stage and the estimate will apply a higher multiplier. Growth is fast and uneven, though, and requirements change week by week, so young animals benefit from frequent weight checks and a veterinarian’s input rather than a fixed number.
The RER equation used for dogs and cats was not developed for those species, so applying it directly would be misleading. Rabbits are estimated per kilogram of body weight and should have unlimited grass hay as the base of the diet, with pellets as a limited portion. Birds use a separate allometric estimate and vary enormously by species. Both outputs are deliberately presented as rough.
One tool, every pet in the house
Run the numbers again whenever the weight, the routine or the food changes.
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