Ask how many words a dog understands and the honest answer is: it depends enormously on the dog, and on what you mean by “understands”.
The research gives us some genuinely interesting numbers.
The average dog
A large survey study asked owners to identify which words and phrases their dogs responded to from a standardised list. The average came out at around 89 words and phrases, with a range from roughly 15 to over 200.
Most of those are practical: the dog’s name, sit, down, stay, come, walkies, dinner, no, off, bed, out, ball, and the names of household members. Many are phrases rather than single words — “get in the car”, “go to bed” — which dogs learn as units.
Herding breeds and working breeds tended to score higher, though the effect of training and how much the owner talks to the dog matters at least as much as breed.
The exceptional dogs
A handful of individual dogs have gone far beyond the average, and they have been studied carefully.
Rico, a Border Collie studied in 2004, knew the names of over 200 objects. More strikingly, he could work out a new one by exclusion: presented with a set of familiar toys plus one unfamiliar one and asked for a name he had never heard, he retrieved the new toy. This is called fast mapping, and it is how human children acquire words rapidly.
Chaser, another Border Collie, learned the names of 1,022 objects over three years of daily training. She could also categorise them — retrieving by “ball” or “frisbee” as well as by individual name — and she understood simple sentences combining a verb and an object, such as “take ball to frisbee”. That is rudimentary syntax, not just vocabulary.
Whisky, a Border Collie studied more recently, demonstrated similar categorisation abilities without the same intensive formal training.
The Genius Dog Challenge, a research project run from Budapest, recruited exceptionally gifted dogs from around the world and found that these individuals could learn new toy names after remarkably few exposures — sometimes as few as four.
What is actually happening in the brain
A 2016 neuroimaging study trained dogs to lie still in an MRI scanner while their trainer spoke to them.
The finding was that dogs process language in a way structurally similar to us. The left hemisphere handled word meaning; the right hemisphere handled intonation. And crucially, the reward centre of the brain lit up most strongly when a praise word was spoken in a praise tone — that is, when meaning and intonation agreed.
Praise words in a neutral tone, or neutral words in a praise tone, did not produce the same response. The dogs were processing both channels and combining them.
More recent work using EEG has suggested dogs form mental representations of objects they hear named — showing different brain activity when presented with an object that did not match the word they had just heard. That is a meaningful step beyond simply learning that a sound predicts an action.
What dogs are probably not doing
It is worth being careful here.
Dogs do not have language. They do not combine words generatively to produce novel meanings. Chaser’s understanding of “take ball to frisbee” is remarkable, and it is a long way from a sentence.
Much of what looks like word understanding is context. A dog that goes to the door when you say “walk” may be responding to the word, or to the time of day, your posture, the fact you have stood up, and where you are looking. Removing those cues often reveals the dog was not listening to the word at all.
Tone carries a great deal. Dogs respond strongly to prosody, and a happy tone with nonsense syllables produces much of the same response as a real cue in many dogs.
The Clever Hans problem is always present. Dogs read human body language extraordinarily well, and unconscious cueing accounts for a good deal of apparent comprehension. Serious studies control for it; casual observation at home does not.
Teaching your dog more words
If you want to expand the vocabulary, object names are the easiest place to start.
- Pick one toy with a distinctive name and appearance.
- Play with it, saying the name repeatedly during play.
- Place it alone on the floor a short distance away and say “get [name]”. Reward heavily for picking it up.
- Add a second toy with a very different name and appearance. Ask for one. If the dog picks the wrong one, say nothing and ask again.
- Build slowly. Two solid names are better than six muddled ones.
Outward Hound Hide-A-Squirrel Plush Puzzle Toy
A set of distinct squeaky pieces inside a plush trunk — useful for naming games because the individual pieces can be given separate names and retrieved on cue.
Some links on this page are affiliate links. If you buy through them we may earn a small commission at no extra cost to you — it helps keep this site free. We only recommend products we would use with our own dogs.
Dog Training Clicker
Marking the exact moment the dog makes contact with the correct object is what makes naming games clear rather than confusing.
Words worth teaching regardless
Practical vocabulary beats an impressive count. The ones that genuinely make life easier:
- A recall word
- “Wait” and a release word
- “Leave it” and “drop”
- “Touch” for a hand target
- “Bed” or “place”
- “Off” for furniture and people, distinct from “down”
- The name of the car, the lead, and dinner
Twelve reliable words are worth more than ninety half-understood ones.
The honest summary
Your dog probably understands something like ninety words and phrases, is reading your tone at least as carefully as your vocabulary, and is combining both with everything else it knows about you.
A small number of extraordinary dogs can learn over a thousand object names and categorise them. Whether your dog could is unknown, and there is really only one way to find out.
