* Small breeds: Typically reach their full size around 6-12 months old.
* Medium breeds: Usually reach their full size around 12-18 months old.
* Large breeds: Can take up to 2-3 years to reach their full size.
Keep in mind that these are just general guidelines. Individual dogs may grow at different paces. It's important to consult your veterinarian for personalized advice on your dog's growth and development.