When do Golden Retrievers stop growing?

Golden Retrievers typically reach their full height by the time they’re about a year old. However, they may continue to fill out in weight and gain muscle mass up to 18 months of age. The exact timing can vary between individual dogs. 

These dogs are also a bit like forever puppies, so it can take up to two years for them to mature cognitively. Proper nutrition and exercise go a long way during this growth phase to ensure they develop healthy muscles and bones.