NNPets
This calculator could not start. It needs JavaScript to do its arithmetic, and that either failed to load or is switched off. The explanations, reference tables and cited sources below all work without it — and the formulas are written out under each calculator, so you can work through them yourself.

How big will my puppy get?

Estimate your puppy's adult weight, their daily calorie needs, how much to feed at each meal, and the crate size worth buying. Every calculation below uses a published formula, and the source is shown next to each result.

Your puppy

Weigh your puppy in the morning, before feeding, for the most consistent number.

The adult-weight formula is most reliable between 12 and 20 weeks.

Food energy density (optional)

Printed on the bag, usually as kcal/kg (also written ME) or kcal/cup. Leave blank to skip portion sizes.

kcal/kg
kcal/cup

Typical dry food is roughly 3,200–4,200 kcal/kg (about 350–450 kcal/cup). Check your bag — guessing here changes the answer a lot.

Results update as you type.

Estimated adult weight

—

How this is calculated

Daily calories

— kcal/day

How this is calculated

Resting energy requirement: RER = 70 × (body weight in kg)0.75

Maintenance energy requirement: MER = life-stage factor × RER

How much to feed

—

How this is calculated

daily food = daily kcal ÷ food energy density

Body condition score is the real feedback loop: weigh your dog regularly and adjust the amount up or down. See the caution below.

Crate size to buy

—

Buy for the adult size, not the puppy size — otherwise you will buy twice.

How this is calculated

How this is calculated

Adult weight uses the formula published by Bond Vet: (current weight ÷ age in weeks) × 52. Their worked example is a 20 lb puppy at 16 weeks, giving 65 lb, and the test suite checks exactly that. The formula assumes constant growth; real puppies decelerate, so past roughly 20 weeks it overestimates. The calculator tells you which reliability band your input falls into rather than hiding that.

Calories come from two independent veterinary sources that agree: the 2021 AAHA guidelines and the Pet Nutrition Alliance. Both give RER = 70 × (kg)0.75 and MER = factor × RER. AAHA’s own example — a 10 lb neutered dog — gives 216 kcal RER and 302 kcal MER, which this tool reproduces.

Portion size is daily calories divided by the energy density on your bag, which is why we ask for it instead of guessing: two foods can differ by more than 30%. Crate size follows estimated adult weight, from the PetSmart sizing chart.

The caveat worth reading. The Pet Nutrition Alliance is explicit that these equations are “ONLY ESTIMATES, as individual animals can vary by as much as 50% from the predicted values.” Use the number as a starting point and let your dog’s body condition tell you whether to feed more or less. We do not diagnose, score body condition, or recommend a specific food — those need a hands-on exam.

Quick answers

How accurate is a puppy weight calculator?

Ballpark only. The formula assumes steady growth, which puppies do not do. It works best between about 12 and 20 weeks; past 4 months it tends to overestimate. Below 8 weeks this site shows no number at all, because the result would be several times the true weight.

How many calories does my puppy need per day?

RER = 70 × (body weight in kg)^0.75, multiplied by a life-stage factor: 3.0 under 4 months, 2.0 from 4 months. The Pet Nutrition Alliance cautions that individual animals can vary by up to 50% from the predicted value.

How much should I feed my puppy?

Daily calories divided by the energy density on your food bag, split across the day’s meals. Treat it as a starting point and adjust using body condition rather than the formula alone.

What size crate should I buy?

Buy for the adult size, not the puppy size, or you will buy twice. Add 2–4 inches to the standing height and to the nose-to-tail-base length. Between sizes, size up.

Is this veterinary advice?

No. It is an educational calculator on published formulas and cannot account for your dog’s health or body condition. Confirm feeding and growth decisions with your veterinarian.

Sources

  1. American Animal Hospital Association (AAHA). Energy Requirement Calculations — 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats. aaha.org
  2. Pet Nutrition Alliance. Calculating Calories Based on Pet Needs. petnutritionalliance.org
  3. Bond Vet. Puppy Growth: What You Need to Know. bondvet.com
  4. Great Pet Care. How Big Will My Puppy Get? greatpetcare.com
  5. PetSmart Learning Center. Dog Crate Size Chart: Finding the Perfect Fit. petsmart.ca

How these sources were chosen, and what this site does not do: about & methodology.

Educational use only. nnpets.com is not a veterinary service and this page does not provide veterinary advice, diagnosis or treatment. Always consult a licensed veterinarian about your dog's diet, growth and health.