Every weight range on this site is calculated from one table: the median percent of adult bodyweight a dog has reached at a given age, by size class and sex. That table is published here in full, with the method used to derive it and the things it cannot tell you. It is free to reuse with attribution.
The table
| Age | Toy | Small | Medium | Large | Giant | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| M | F | M | F | M | F | M | F | M | F | |
| 2 months | 36% | 37% | 31% | 33% | 27% | 28% | 23% | 24% | 19% | 20% |
| 3 months | 49% | 49% | 46% | 47% | 42% | 43% | 38% | 39% | 32% | 34% |
| 4 months | 61% | 62% | 59% | 60% | 56% | 56% | 51% | 52% | 45% | 47% |
| 5 months | 70% | 70% | 70% | 70% | 68% | 67% | 64% | 65% | 57% | 59% |
| 6 months | 77% | 76% | 77% | 77% | 76% | 74% | 74% | 74% | 67% | 68% |
| 8 months | 85% | 84% | 87% | 86% | 86% | 85% | 87% | 86% | 83% | 82% |
| 10 months | 90% | 88% | 91% | 90% | 92% | 90% | 93% | 92% | 90% | 90% |
| 12 months | 92% | 92% | 93% | 92% | 92% | 91% | 94% | 94% | 92% | 92% |
| 18 months | 96% | 95% | 98% | 97% | 98% | 97% | 98% | 97% | 98% | 97% |
| 24 months | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% |
Multiply any figure by an adult weight to get the expected weight at that age. A male large-breed dog heading for 70 lb is at 38% of that at three months, so about 27 lb. The full file linked above carries the 10th, 25th, 50th, 75th and 90th percentiles for every month from 2 to 24, along with the sample size behind each cell.
How it was derived
The source is Salt C, Morris PJ, Wilson D, Lund EM, German AJ (2017). Growth standard charts for monitoring bodyweight in dogs of different sizes. PLoS ONE 12(9): e0182064, published open access, and its accompanying dataset at University of Liverpool DataCat under a CC BY 4.0 licence. The dataset holds 14,957,947 bodyweight records collected at Banfield Pet Hospitals, a network of over 900 primary-care veterinary clinics in the United States, between 1994 and 2013.
Records were kept where the visit was for preventive care or carried a healthy-pet diagnosis, and dropped where body condition had been recorded as thin or heavy. That left 8,459,668 records, 56.6% of the file. Each dog’s weight was divided by the average adult weight of its breed, which the dataset supplies, and the resulting ratios were grouped by size class, sex and age in months. Percentiles were taken within each group and then normalised so that the median at 24 months reads as 100%.
Breed identifiers in the source are anonymised, which turns out not to matter: the study’s central finding is that dogs of similar adult size grow at similar rates regardless of breed, so the average adult weight per breed is all that is needed to group them.
What it cannot tell you
- It is not an ideal-weight standard. Body condition was unrecorded on 93% of rows, so only dogs recorded as thin or heavy could be excluded. What remains describes dogs attending veterinary clinics, not a screened healthy population.
- The medium class is interpolated. No breed in the source averages between 14 and 23 kg as an adult, which is the middle of that class. Its curve is inferred from the classes either side and is the least certain of the five.
- The giant class is ours, not the study’s. The published models could not be fitted above 40 kg. Those figures are percentiles we calculated from the same raw records; the study does not certify them.
- The records end in 2013 and are from US clinics. Growth physiology is not fast-moving, but the population is what it is.
- Below 8 weeks is excluded. There are records, but they are sparse and skewed: a six-week-old puppy at a clinic is more often there because something is wrong.
Reproducing it
Three short Python scripts take the source file to the published table in about eighty seconds on a laptop. Download the 146 MB dataset, filter it, take percentiles, normalise. If you want to check the arithmetic rather than trust it, that is the whole of it:
curl -L https://datacat.liverpool.ac.uk/377/5/Final_Data_PLOS.zip -o data.zip
# filter to preventive-care visits, exclude recorded thin/heavy, months 2-24
# group by size class x sex x month, take percentiles of weight / breed adult average
# normalise so the 24-month median reads 100%Using this data
The underlying dataset is CC BY 4.0 and the derivation here is offered on the same terms. Use it, republish it, build on it — the only ask is attribution, which the licence on the source requires in any case.
Suggested citation
PupTimeline (2026). Canine growth curves by size class.
Derived from Salt C, Morris PJ, Wilson D, Lund EM, German AJ (2017),
PLoS ONE 12(9): e0182064, CC BY 4.0.
https://puptimeline.com/growth-data/puptimeline-growth-curves.csv — 230 rows, one per size class, sex and month, with five percentiles and the sample size behind each.
Is this the WALTHAM growth chart?
No, though they share an origin. The WALTHAM Puppy Growth Charts are a clinical tool built from the same research programme and published by the WALTHAM Petcare Science Institute. Those charts are copyrighted and are not reproduced here. The figures on this page are calculated independently from the open-access dataset that accompanies the published paper, which anyone is free to do.