How Far Can A Dog Smell?
There is no straightforward answer regarding how far a dog can smell. There are too many variables to consider when measuring up to what distance a dog can smell like weather and wind direction, the concentration of objects in between the dog and the object, and the familiarity of the scent, to name a few.
However, there are other ways to quantify a dog's sense of smell that relate to how far a dog can smell. Empirical data show that dogs can smell a scent in terms of parts per trillion. This means that dogs can distinguish a particular odor in the middle of almost innumerable other smells. This could mean that a dog can smell up to 40 feet underground, 80 feet over the water, or a mile away considering favorable conditions.
To compare with humans, dogs have 220 million olfactory receptors whereas humans only have 6 million. This is not surprising as smell is the primary sense used in survival by dogs to find mate, to hunt food, and to avoid danger such as predators. They also have a unique organ called Jacobson's organ that is dedicated to smelling pheromones which are chemical cues secreted by animals.