In-depth guide · Growth
How big will my puppy get? What real growth data shows
How to estimate your puppy’s adult weight from its weight, age and size class, with honest ranges, a worked example and why calculators disagree.
Growth
Puppy weight calculator: how big will my puppy get?
Your puppy’s likely adult weight from age, weight and breed or size, with the range half of puppies like yours end in.
Puppy weight calculator
ExampleA 16-week-old male Labrador Retriever weighing 25 lb · size class V (large)
Your estimate · adult weight
about61lb
A 16-week-old male Labrador Retriever weighing 25 lb will most likely weigh about 61 lb as an adult. Half of puppies like him end between 55 and 69 lb; 8 in 10 between 51 and 79 lb.
- Grown now
- 41%of adult weight
- Size class
- Large · V66–88 lb adults
- 90% grown
- 10½ monthsat 46 weeks
- 95% grown
- 16½ monthsat 72 weeks
Sources checked How the math works Data and sources
- most likely path
- half of puppies
- 8 in 10
- today
The jug on the left shares the chart’s scale: full is the likely adult weight, so its level shows how much of it is already there (41%). Rings on the path mark where the median puppy of this size reaches 90% and 95% of adult weight.
Growth bands derived by Puppy Scale from Salt C et al. (2017), PLOS ONE 12(9):e0182064, data: University of Liverpool DataCat 377, licensed CC BY 4.0. Our tables are empirical summaries, not the published model curves. Changes: see the method.
Breed weights: Andersson L et al. (2023) Scientific Reports 13:443 (CC BY 4.0); Bannasch D et al. (2021) Canine Medicine and Genetics 8:12 (CC BY 4.0); O’Neill DG et al. (2023) PLOS ONE and (2026) Canine Medicine and Genetics, VetCompass UK (CC BY 4.0); Hayward JJ et al. (2016) Nature Communications (CC BY 4.0). Kennel-club breed standards: see the club’s own breed page.
Why age matters: the same 25 lb at another age
A younger puppy at the same weight is headed for a bigger adult. Tap an age to use it above.
Where the size class came from
Labrador Retriever is in the large class (66–88 lb adults) in the growth study’s own breed table.
- Young adults measured in Sweden: males 69 lb, females 58 lb — Andersson et al. (2023), Scientific Reports 13:443, CC BY 4.0
- Pet dogs in UK vet records (adult median): males 74 lb, females 64 lb — O’Neill et al. (2023), PLOS ONE 18(7):e0288081, CC BY 4.0
- Mid-range of breed-standard weights: 68 lb — Bannasch et al. (2021), Canine Medicine and Genetics 8:12, CC BY 4.0
These figures are context: they pick the size class and never cap the estimate. Size classes for breeds the study lists: Salt et al. (2017), Table 1, CC BY 4.0. Kennel-club breed standard: see the club’s own Labrador Retriever page.
Rules of thumb, tested on large dogs
- “Double the weight at 16 weeks”would say 50 lb for this puppy; in this data that rule runs 19% low for this size (median), and only 24% of dogs land within 10%.
- “Double the weight at 4 months”in this data that rule runs 9% low for this size (median), and only 42% of dogs land within 10%.
- “Double the weight at 6 months”in this data that rule runs 38% high for this size (median), and only 7% of dogs land within 10%.
Each rule checked against the real adult weights of thousands of dogs in the same data (derived from Salt et al. 2017, CC BY 4.0).
Talk to your vet. This is an estimate, not veterinary advice. Puppy Scale is not a veterinary practice and can’t examine your pet.
Estimate by Puppy Scale · sources checked October 7, 2026 · not veterinary advice · puppyscale.com
How the math works
Each step below is one rule, with the data it comes from and the date we read it. The example is the house puppy: a 16-week-old male Labrador Retriever weighing 25 lb.
- Size class
Six classes by adult weight: I under 6.5 kg (14.3 lb); II 6.5 to under 9 kg (14.3–19.8 lb); III 9 to under 15 kg (19.8–33.1 lb); IV 15 to under 30 kg (33.1–66.1 lb); V 30 to under 40 kg (66.1–88.2 lb); VI 40 kg (88.2 lb) and over. A breed listed in the growth study’s own breed table keeps that class; otherwise the breed’s measured young-adult weight for the sex decides it (Swedish screening data, then UK vet records), then published breed mid-ranges.
Parents’ weights: their average decides the class. A DNA test: its adult estimate decides the class (the company’s claim). “I don’t know”: the class whose band contains its own estimate.
Growth standard charts for monitoring bodyweight in dogs of different sizes (PLOS ONE 12(9):e0182064), read · Exploration of body weight in 115 000 young adult dogs of 72 breeds (Sci Rep 13:443), read · Dog breeds and conformations in the UK in 2019: VetCompass canine demography and some consequent welfare implications, read · The effect of inbreeding, body size and morphology on health in dog breeds (Additional file 1), read · Complex disease and phenotype mapping in the domestic dog (Supplementary Data 2), read
- Share of adult weight
For each class and 13 ages from 8 to 78 weeks, the 10th, 25th, 50th, 75th and 90th percentile of each dog’s weight divided by its own adult weight (its median weight at 2–3 years); straight lines between those ages. A large-class puppy at 16 weeks: median 40.7% of adult weight.
Growth standard charts for monitoring bodyweight in dogs of different sizes (PLOS ONE 12(9):e0182064), read · Growth standard charts for monitoring bodyweight in dogs of different sizes - SUPPORTING DATA, read
- The estimate
Most likely = today’s weight ÷ the median share: 25 lb ÷ 0.407 = 61 lb. Half of puppies: today’s weight ÷ the 75th and ÷ the 25th percentile (55–69 lb). 8 in 10: ÷ the 90th and ÷ the 10th (51–79 lb).
No lower end is ever below today’s weight: an adult can’t be estimated lighter than the puppy is now.
- The drawing
The most likely path is today’s weight × the median share at each age ÷ the median share today; both ranges open in the same proportion and end at the adult numbers. The jug uses the same scale: full is the likely adult weight.
- When growth ends
The age at which the median dog of each class reaches 90% and 95% of adult weight, in weeks: toy 60 / 88 · small 46 / 72 · medium 58 / 84 · medium-large 48 / 80 · large 46 / 72 · giant 50 / 78. Large class: about 10½ months and about 16½ months.
Growth standard charts for monitoring bodyweight in dogs of different sizes (PLOS ONE 12(9):e0182064), read · Growth standard charts for monitoring bodyweight in dogs of different sizes - SUPPORTING DATA, read
- Rules of thumb
Each folk rule (“double the weight at 16 weeks”, “at 4 months”, “at 6 months”) applied to every dog in the same data and compared with its real adult weight: the median error and the share of dogs within 10%.
Growth standard charts for monitoring bodyweight in dogs of different sizes (PLOS ONE 12(9):e0182064), read · Growth standard charts for monitoring bodyweight in dogs of different sizes - SUPPORTING DATA, read
- The edges
Under 8 weeks: Not modeled (the data starts at 8 weeks). 8 to 12 weeks: an early estimate (the published charts start at 12 weeks). Over 78 weeks: Not modeled (growth is essentially complete). Over 40 kg adults: less predictable — the study did not model those sizes.
Growth standard charts for monitoring bodyweight in dogs of different sizes (PLOS ONE 12(9):e0182064), read · Neonatal puppy weight gain (review), read
- Toy breeds
An older study of a dozen breeds put toy puppies at about 53% of adult weight at 12 weeks; the much larger data used here gives about 39%. Sources disagree, so for toy breeds the true range is likely wider than shown.
Shown as context only; the calculator uses the larger data set.
What this doesn’t cover
Breed-specific growth curves: Not modeled — no openly licensed breed curves exist, so breeds only choose the size class (checked October 7, 2026).
Blending the parents’ weights into the estimate: Not modeled — no published method has been validated; the parents only choose the size class (checked October 7, 2026).
Paw size: Not modeled — we found no evidence that paw size predicts adult weight (checked October 7, 2026).
Height: Not modeled — the data are weights only (checked October 7, 2026).
Neutering: Not modeled — in the study its effect on growth was small next to the differences between dogs, so it is not an input (checked October 7, 2026).
Data licences
Growth bands derived by Puppy Scale from Salt C et al. (2017), PLOS ONE 12(9):e0182064, data: University of Liverpool DataCat 377, licensed CC BY 4.0. Our tables are empirical summaries, not the published model curves. Changes: see the method.
Breed weights: Andersson L et al. (2023) Scientific Reports 13:443 (CC BY 4.0); Bannasch D et al. (2021) Canine Medicine and Genetics 8:12 (CC BY 4.0); O’Neill DG et al. (2023) PLOS ONE and (2026) Canine Medicine and Genetics, VetCompass UK (CC BY 4.0); Hayward JJ et al. (2016) Nature Communications (CC BY 4.0). Kennel-club breed standards: see the club’s own breed page.