At 7 months, a black Lab is not quite yet an adult dog.
By 7 months old your black Labrador retriever is no longer a puppy. She should be almost full adult height, although she won’t yet reach her adult weight. Male and female Labs grow to different sizes, so her size at this age won’t be the same as a male’s.
The average female black Lab grows to a height of between 21 and 24 inches from the floor at the withers, or shoulders, although even a purebred dog can be bigger or smaller. Males reach a height of 22 to 25 inches. By the age of 6 months, most dogs reach approximately 75 percent of their full adult height, so your 7-month-old black Lab should be between 15 and 18 inches tall.
A healthy adult black Lab female weighs 55 to 70 pounds and a male 65 to 80 pounds. By the age of 6 months, black Lab puppies reach approximately two-thirds of their adult weight, so a dog of 7 months should be in this range or slightly heavier. At 70 percent of the average female adult weight, your female black Lab puppy should weigh from 40 to 50 pounds, while a male puppy would weigh between 45 and 55 pounds.
Black Lab puppies go through a stage from the age of 4 months to around 7 months, when their legs appear to grow much faster than the rest of their bodies. This gives them the look of a teenager with long, gangly legs and big paws. By the age of 1 they grow into proportion, but at 7 months it’s likely your black Lab still has rather long legs for her body. Her paws, though, are likely to be full adult size, which will make them look larger because they're out of proportion with the rest of her young body.
At the age of 7 months, your black Lab’s muscles are not yet fully developed. As a large-breed dog, Labs commonly reach maturity at around 12 to 18 months; some take even longer to develop. A nonadult black Lab may look fairly skinny and have the appearance of slinking along like a cat when she walks: though her height is almost that of an adult dog, she has months to go before she fills out.