How Amazing Is a Dog's Sense of Smell? Why Sniff Time on Walks Matters

On a walk, your dog may stop at the base of a utility pole or in front of a hedge and refuse to move. On busy days, it is tempting to tug the leash.

Yet for a dog, that pause is valuable time for learning about its surroundings. This article looks at how remarkable a dog's sense of smell is, using material from public agencies and professional organizations. By the end, you should know how to make room for sniffing on walks and outings.

"How many times better than a human?" depends on the source

Among the sources we checked in October 2026, there is no single answer to how many times stronger a dog's sense of smell is than ours. According to a police dog profile from the Hokkaido Prefectural Police, it is said to be 3,000 to 100 million times stronger than ours.

Customs sources differ as well: Nagasaki Customs gives about 5,000 to 20,000 times, while Moji Customs says tens of thousands of times. Sources outside Japan give figures such as 100,000 or 1 million times.

All three Japanese sources use the phrase "it is said." There is no fixed figure, but every source agrees that a dog's nose works on a completely different scale from ours. Nagasaki Customs also mentions an experiment in which dogs detected the smell of acetic acid, such as vinegar, even when it was diluted a million times.

Smells enter through olfactory receptors inside the nose

According to a joint release by the Japan Science and Technology Agency (JST) and the University of Tokyo, the entry point for smell is the olfactory receptors. These proteins recognize odor molecules and sit on nerve cells in the olfactory epithelium, the lining inside the nasal cavity that picks up smells.

The University of Tokyo explains that the ability to tell smells apart depends on the types and number of these receptors. According to an AKC article, dogs have 100 million or more scent receptors in their noses depending on the breed, while humans have about 5 to 6 million.

The nose has another clever feature. The AKC says the shape of a dog's snout means the air it breathes out does not disturb the scent it is analyzing.

The Merck Veterinary Manual lists finding drugs and searching for missing people as jobs that make use of a dog's ability to detect very faint odors. Putting this nose to work, customs drug detection dogs and the quarantine detector dogs of the Ministry of Agriculture, Forestry and Fisheries check luggage by smell at Japan's airports and seaports. Quarantine detector dogs sit to alert their handler when they find the smell of meat products, fruit or similar items.

Sniffing on walks is how dogs learn about their surroundings

Sniffing on a walk is how a dog gathers information. The AKC also explains that dogs use scent to learn about their environment and the animals that share it.

For dogs, smell tells them more than how something looks, sounds or tastes. One AKC article even calls the scent left on a fire hydrant "pee-mail." No wonder dogs stop at the base of utility poles.

The AKC says time spent investigating scents also offers mental enrichment, a chance to make choices, and stress relief. On scent-focused walks, an expert in the article lets her dogs choose where to go and how long to spend investigating smells. Because it takes concentration and raises the breathing rate, it is surprisingly tiring.

In another article, the AKC recommends giving dogs plenty of chances to sniff on walks, because smelling provides important information and essential mental stimulation. It also suggests rewarding short stretches of loose-leash walking with frequent sniff breaks.

Pair sniff time with consideration for others

When letting your dog sniff, hold the leash short and step to the side of the path. It is safest to skip other people's gates, walls and venue entrances as sniffing spots. Waiting at the side also makes it easier for people and dogs to pass. When sniff time is over, give your cue before you walk on instead of suddenly pulling the leash.

Kobe City asks owners not to let their dogs urinate on other people's doors or walls, and to rinse it away with water if they do. It also recommends keeping the leash at a length that lets owners control their dog. The city adds that dogs should be walked by someone who can control them.

On outing days, plan sniff time before and after your venue visit

On days you visit a venue with your dog, try scheduling sniff time on the way there and on the way home. An AKC article says the best places for a sniff walk have plenty of grass, trees, bushes and natural ground. If the venue is near a park, it is easier to combine a walk and your visit into one outing.

Some parks have rules about where dogs may go, so check the park's information beforehand as well. After a good sniff in the park, give your "move on" cue before you reach the venue entrance. Save a little sniff time for the way home, too.

On Inucomi, you can search for venues near a park, venues surrounded by greenery and venues with terrace seating. Dog policies differ from venue to venue, so check the dog rules section on each venue's page before you go.

You can review how a dog's body works with the How Dogs Work Quiz: Beginner. Take What Is Your Dog's Walking Style? to find the kind of venue that suits how your dog likes to walk.

On your next walk, try waiting a little when your dog stops to sniff. Watching where your dog stops will also show you its favorite spots.