Border Collie puppy growth: milestones and weight estimates
How fast a Border Collie puppy grows, illustrative weight estimates and the limits of predicting adult size.
Border Collie puppies are usually around 5 to 7 kg at 12 weeks and approach adult weight by 12 to 15 months. Height is mostly done by 10 to 12 months, but the mind develops much later, and many lines do not feel mentally settled until two or three years old. Adolescence, from roughly 6 to 18 months, is often when herding behavior and reactivity to movement appear.
Young collies tend to throw themselves into activity with no off switch, so it is up to you to limit repetitive, high-impact work while growth plates close. Avoid endless ball throwing, long runs and full-height agility jumps before about 12 to 18 months, and teach the puppy to rest in a crate or pen between sessions. A puppy that cannot settle even after exercise usually needs more calm practice, not more running.
Border Collie puppy growth in numbers
Illustrative size-based model for a male Border Collie, in kg, by age in months
| Age | Female | Male |
|---|---|---|
| 2 months | 3.2 kg | 3.5 kg |
| 3 months | 5 kg | 5.5 kg |
| 4 months | 6.9 kg | 7.6 kg |
| 5 months | 8.5 kg | 9.3 kg |
| 6 months | 9.8 kg | 11 kg |
| 7 months | 11 kg | 12 kg |
| 8 months | 12 kg | 13.5 kg |
| 9 months | 13 kg | 14.5 kg |
| 10 months | 13.5 kg | 15 kg |
| 12 months | 15 kg | 16.5 kg |
| 14 months | 15.5 kg | 17 kg |
| 15 months | 15.5 kg | 17 kg |
This is an editorial model scaled to a typical adult weight, not an observed breed average, a validated growth standard or a healthy-weight range. Do not adjust food to make a puppy follow this line. Discuss actual growth measurements with your vet.