Dog Calorie Needs (RER → MER)
Estimate daily dog calories and portions
Dog calorie needs and RER → MER FAQ
What are RER and MER for dogs?
RER stands for Resting Energy Requirement: the energy a healthy dog would use just to run basic body functions at rest. MER is Maintenance Energy Requirement: RER multiplied by a factor that accounts for real life — activity, growth, neuter status, and more. This calculator works out RER from your dog’s weight in kilograms, then applies a lifestyle factor to estimate MER.
Why do you show both pounds and kilograms?
The underlying veterinary formulas are written in kilograms, but many U.S. dog owners think in pounds (lb). You can enter weight in lb or kg, with lb selected by default for a U.S.-first experience. The tool converts between units in the background and shows both lb and kg in the summary so you can cross-check against vet charts and international feeding guides.
How do I pick the right life stage and activity profile?
Use the lifestyle dropdown as a rough guide, not a diagnosis. A calm, neutered indoor dog usually fits the neutered adult house pet setting. A very active dog that hikes or works most days may belong in the active / working band. Growing puppies use the puppy 0–4 months or puppy 4–12 months options. When in doubt, start with a middle option and ask your veterinarian which factor makes sense for your dog’s body condition.
Why does my vet’s calorie number look different?
Vets often start with similar formulas but then tweak calories up or down based on your dog’s body condition score, lab work, lifestyle and medical history. Some clinics also use brand-specific tools that bake in extra safety margins. If your vet’s number disagrees with this calculator, follow your vet and use this page just as a way to understand how the math works.
What does the cups or grams per day result mean?
When you enter kcal per cup or kcal per 100 g from your food label, the calculator divides your dog’s MER by that number. The result is an estimated number of level measuring cups or grams per day, then a simple two-meal AM/PM split. It assumes you measure accurately and feed only that main diet, without lots of extra treats.
Can I use this for weight loss or weight gain plans?
There is a weight-loss plan profile that uses a lower MER factor, but any weight change plan should be supervised by your vet. Rapid weight loss can be risky, and some medical conditions look like simple weight gain or loss at first. Use the calculator as a starting point, then get a professional check before you make big changes.
How often should I recalculate my dog’s calories?
For adult dogs at a stable weight, recalculating a few times a year is usually enough. Growing puppies benefit from more frequent updates as they gain weight and shift life stages. Seniors and dogs with chronic disease may need tighter monitoring. Any time your dog’s weight or body condition changes noticeably for more than a couple of weeks, it is worth updating the weight here and talking to your vet.
Do treats, chews and table scraps count?
Yes. Calories from treats and extras can add up quickly. Many vets suggest keeping treats under about 10% of daily calories. The calculator’s MER is for total daily intake, so if a lot of calories come from treats, the amount of main diet may need to go down. If you are unsure, track everything your dog eats for a few days and ask your vet or nurse team to help interpret it.
How to use this dog calorie needs calculator
This calculator turns your dog’s weight in pounds or kilograms and a simple lifestyle profile into a daily calorie estimate using the standard RER → MER method. If you add food label calories, it also shows how many cups or grams of that diet to feed per day and per meal, using a straightforward AM/PM schedule.
1. Weigh your dog in lb or kg
Start by entering your dog’s weight and choosing lb or kg in the small units box. U.S. owners can leave it on lb; if your vet gave you a kg weight you can switch to kg. The tool converts between lb and kg automatically and uses the kilogram value in the RER formula. Both units are shown in the results for easy checking.
2. Choose a life stage and activity profile
Next, pick the profile that best matches your dog right now: neutered adult pet, intact adult, very low-activity or senior, active or working dog, or one of the puppy ranges. Each profile is linked to a MER factor that multiplies RER to account for growth, exercise, and other daily demands. It is fine to adjust this choice over time if your dog’s routine changes.
3. Add food label calories (optional but powerful)
If you want real cups or grams per day, look at your food bag or can:
- For dry foods, use the number listed as kcal per cup or per 8 oz measuring cup.
- Some labels show kcal per 100 g; that works too.
- Enter the number and choose the correct basis (cup or 100 g) in the small dropdown.
If you skip this step, the calculator will still show daily calories but not portion sizes.
4. Read RER, MER and portion suggestions
When you tap Calculate calories, the summary card shows:
- Your dog’s weight in lb and kg.
- The calculated RER in kcal/day.
- The MER factor based on your profile and resulting MER calories/day.
- Cups per day and per meal or grams per day and per meal, if you entered label kcal.
Portions are split into two equal meals for a simple AM/PM feeding schedule. If you feed three or more meals, you can divide the daily amount again by the number of bowls.
5. Save the plan and monitor body condition
Use the Copy summary button to drop the results into a notes app or email. Over the next few weeks, watch your dog’s weight, waistline and energy. If weight drifts up or down, or if your vet flags a concern, adjust calories or the MER factor with their guidance. The math here is a starting point, not a fixed rule.
Think of this page as a dog calorie and portion math helper that keeps the numbers tidy while you and your vet decide what is right for your individual dog.
How the dog calorie needs math works
The equations behind this tool follow widely used veterinary guidelines for estimating Resting Energy Requirement (RER) and Maintenance Energy Requirement (MER). They are intentionally simple so you can check them with a calculator or spreadsheet if you like.
1. Converting between pounds and kilograms
Veterinary calorie formulas use kilograms, so the first step is:
Weight (kg) = weight (lb) ÷ 2.2
Weight (lb) ≈ weight (kg) × 2.2
A 44 lb dog weighs about 20 kg. The calculator keeps a precise internal value but rounds the display for readability.
2. Calculating Resting Energy Requirement (RER)
The standard RER formula is:
RER (kcal/day) = 70 × (body_weight_kg0.75)
This “power 0.75” term scales energy needs to body size without assuming that big dogs are simply “scaled-up” small dogs. It reflects how metabolism changes with size.
3. Applying MER factors for real life
To estimate daily calories in the real world, RER is multiplied by a lifestyle factor:
MER (kcal/day) = RER × factor
In this tool, the factor is typically:
- ~1.6 for a neutered adult house pet.
- ~1.8 for an intact adult.
- ~1.0 for many weight-loss programs.
- ~1.2 for very low-activity or some seniors.
- ~2.0+ for highly active or working dogs.
- 2.0–3.0 for growing puppies, depending on age.
These are mid-range values; your vet may nudge them up or down for your dog.
4. Turning calories into cups or grams
Once MER is known, the food label connects calories to portions. If the label shows:
- kcal per cup, then cups/day = MER ÷ kcal_per_cup.
- kcal per 100 g, then grams/day = MER ÷ kcal_per_100g × 100.
The tool rounds cups to two decimals and grams to the nearest 5 g, then halves the daily amount again to show AM and PM meal sizes. It assumes you use a standard measuring cup and level scoops.
All of these steps are meant to give you a realistic, checkable estimate, not a perfect prescription. The final calorie and portion decisions should always be made with your veterinarian, especially for puppies, seniors, and dogs with medical conditions.
References and further reading on dog calories
Use these guides alongside this RER → MER dog calorie calculator:
- WSAVA Global Nutrition Committee Guidelines — international recommendations on assessing body condition, calorie needs and diet selection.
Your own veterinarian is the best source of truth for calorie targets, weight management plans and how to adjust MER for your individual dog’s health and lifestyle.