How Big Will My Dog Get? Puppy Growth Calculator
Predict how big your puppy will get — adult-weight prediction with a science-based growth curve
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Puppy weight chart by size category
Typical weight development from newborn to the first birthday — computed with the same growth engine as the calculator above (reference: the midpoint of each size category).
| Age | Toy | Small | Medium | Large | Giant |
|---|---|---|---|---|---|
| Week 1 | 270 g | 420 g | 660 g | 840 g | 1.1 kg |
| Week 2 | 330 g | 570 g | 940 g | 1.3 kg | 1.7 kg |
| Week 4 | 490 g | 950 g | 1.7 kg | 2.6 kg | 3.5 kg |
| Week 6 | 670 g | 1.4 kg | 2.8 kg | 4.5 kg | 6.3 kg |
| Week 8 | 870 g | 2.0 kg | 4.1 kg | 7.0 kg | 10.0 kg |
| Week 10 | 1.1 kg | 2.6 kg | 5.6 kg | 9.9 kg | 14 kg |
| Week 12 | 1.3 kg | 3.2 kg | 7.1 kg | 13 kg | 19 kg |
| Week 16 | 1.8 kg | 4.4 kg | 9.9 kg | 19 kg | 30 kg |
| Week 20 | 2.2 kg | 5.3 kg | 12 kg | 24 kg | 39 kg |
| Week 26 | 2.6 kg | 6.3 kg | 15 kg | 29 kg | 49 kg |
| Week 39 | 3.2 kg | 7.2 kg | 17 kg | 34 kg | 59 kg |
| Week 52 | 3.4 kg | 7.4 kg | 17 kg | 35 kg | 62 kg |
Reference values for a dog in the middle of each size category. Individual variation is wide — a steady curve matters more than any single value.
How the puppy growth calculator works
The foundation is the Gompertz growth function W(t) = A · exp(−exp(−B·(t−M))): fast growth in the first weeks of life, then a gentle approach to the adult weight A. It is the validated standard growth model for dogs.
We calibrate the curve shape (B and M) per size class to two anchors from the veterinary literature: birth weight as a fraction of adult weight, and week-8 weight (the classic vet multiplier).
From your weigh-in the calculator derives the implied adult weight and combines it with the selected size category into a prediction with an honest range. Breeders on HonestDog use the same engine in the litter journal — there the prediction sharpens with every additional weigh-in and is refined with the parents' weights.
Frequently asked questions about puppy growth
How accurate is the adult-weight prediction?
With a single weigh-in the prediction is an informed estimate with a range. The closer the puppy is to weeks 8–12, the more reliable it gets. Breeders who weigh regularly in the HonestDog litter journal get a much more precise prediction from multiple data points.
How much should a puppy weigh at 8 weeks?
As a rule of thumb, an 8-week-old puppy weighs about a quarter (small breeds) to a sixth (giant breeds) of its adult weight. An 8-week-old Labrador puppy (adult weight ~30 kg) is typically at 5–7 kg.
When is a dog fully grown?
Small breeds are largely full-grown at 9–12 months, medium breeds at 12–15 months, large breeds at 15–18 months, and giant breeds only at 18–24 months. Skeletal growth finishes before muscle development.
Does the birth weight really double in the first week?
Yes — healthy puppies double their birth weight in roughly 7–10 days. If weight stalls in the first days or the puppy loses weight, the breeder should monitor closely: sustained weight loss is a vet-visit signal.
Can I infer the breed from a puppy's weight?
No — it works the other way around: the breed (or the parents) sets the expected window, and the puppy's weight shows where in that window it sits. For mixed breeds, age + weight still gives a useful estimate.
What is the Gompertz growth curve?
The Gompertz function describes growth with a fast start and a gentle taper to the adult weight — it is the best validated growth model for dogs and also underlies the Waltham growth standards. Our calculator calibrates the curve shape per size class.
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