What size of collar for a 16 week old Labrador?

When it comes to choosing the appropriate size of collar for your Labrador, or any breed of dog there is a simple rule of thumb that I like to use. You want to be able to slide two fingers inbetween your dog's neck and the collar, and if you can do this then the collar is the perfect size for your dog or puppy. If you are only able to slide one finger into the space between your dog's neck and the collar, then that is a sure sign that the collar is tighter than it should be. On the other hand, if there is room for three or four fingers between your dog's neck and the collar, then that is a sign that the collar is oversized.