Border Collie Weight Chart by Age

An adult male Border Collie weighs 30.0–54.9 lb (13.6–24.9 kg) and an adult female 30.0–54.9 lb (13.6–24.9 kg), according to the American Kennel Club breed standard.

A male is typically 12.8–23.4 lb (5.8–10.6 kg) and a female 13.0–23.8 lb (5.9–10.8 kg) — around 43% of adult weight.

Roughly 16.8–30.6 lb for a male and 17.0–30.9 lb for a female, about 56% of the way to adult weight.

A male is usually 22.7–41.7 lb (10.3–18.9 kg) and a female 22.3–40.6 lb (10.1–18.4 kg).

27.8–50.7 lb for males and 27.3–50.0 lb for females — about 92% of final weight, with the rest filling in over the following months.

At 56% of adult weight by 4 months, a rough shortcut is to double a four-month weight. The calculator on the home page does this properly, using the growth curve for this size class and returning a range rather than one number.

Height is usually settled by about 12 months, but a Border Collie keeps filling out until around 15 months. The last 8% of adult weight takes roughly as long as the jump from 3 to 4 months.

Yes, and by enough to matter. Adult males run 30.0–54.9 lb against 30.0–54.9 lb for females. Comparing a female against a chart that does not separate the sexes will usually make her look underweight when she is not.

A medium breed, defined by adult weight. That classification determines the growth curve used here: veterinary research shows dogs of similar adult size grow at similar rates regardless of breed.

Not necessarily. The table shows the middle of the healthy range, so plenty of healthy puppies sit below it. A puppy that is consistently below and not gaining, or that has dropped from a higher line to a lower one, is worth a vet visit. A single reading below the range is not.

Body condition tells you more than the scale. You should be able to feel the ribs under a thin layer of fat without pressing, see a waist from above, and see the belly tuck up from the side. A dog can sit inside the weight range and still carry too much fat.

Most published charts come from one breeder’s litters or from unsourced rules of thumb, and many do not say whether the figures are for males, females or both. The ranges here come from centile curves fitted to millions of veterinary bodyweight records, scaled to the AKC adult range, and split by sex.

The research behind these curves found neutering shifted growth trajectory only slightly, by less than the variation between individual dogs, so separate curves were not needed. Neutering is associated with a higher chance of becoming overweight in adulthood, which is a body condition question rather than a growth chart one.