When Do Bernese Mountain Dogs Calm Down?

By the Riverside Berner Guide editorial team
Last updated November 7, 2026

When do Bernese Mountain Dogs calm down? No source we could find gives an exact age. The Bernese Mountain Dog Club of America (BMDCA) says the breed can be slow to mature, and that young Berners can be very active compared with the trained, often mellow adult.

Research on dogs in general fills in some of the picture. It points to a bumpy teenage stretch, a calmer second year in large dogs, and activity that keeps dropping with age. Training shapes the result as much as the calendar does.

When do Bernese Mountain Dogs calm down? What the breed club says

The BMDCA is the breed’s national club in the US, and it’s the most direct source on Berner behavior. Its 2024 FAQ makes three points worth knowing:

• Slow to mature. The breed can take its time growing up, and young dogs can be very active next to the trained, often mellow adult.
• Bodies first, brains later. Many Berners’ bodies grow faster than their “brains,” which the club says can be hard on inexperienced owners.
• A mouthy phase. Many Berner puppies go through a stage of using their mouths, which young children can encourage without meaning to.

The club doesn’t put an age on any of these. It describes the change, not a date.

The adult you’re working toward

With the training a large working breed needs, the FAQ says adult Berners are generally gentle, easygoing and tolerant. The AKC’s breed page describes them as generally placid, but always ready for a romp with the owner they love to please.

Notice the condition in the club’s wording. The calm adult comes with training, not just with age.

The stages of a Berner’s first years

Each source below describes a different slice of growing up. Only the BMDCA’s is written about Berners.

Puppyhood, by the BMDCA’s timeline

The BMDCA’s puppy’s first year sheet walks through puppy development in stages. A few matter most for behavior:

• 8 to 11 weeks: Puppies are very sensitive to frightening things, and a scary or painful experience can leave a lasting mark.
• 12 to 16 weeks: Puppies start testing boundaries.
• 16 weeks through six months or longer: The club calls this the flight instinct period and adolescence, with a second fear phase. Puppies may suddenly shy away from new or even familiar things.

For that second fear phase, the club advises patience. It says not to force the puppy toward what scares it, and not to baby it either, but to turn the situation into a good experience.

Some milestones do come in the first year. The same sheet says that with consistent training, house-training should usually be done by 8 months of age at the latest.

Adolescence: the teenage months

The AKC says adolescence may begin around eight months and last until about two years, though every dog is different. Dogs get bigger and stronger, act more stubborn, and may seem to forget their training. The AKC also describes a second chewing phase between 8 and 10 months.

This catches many owners off guard. The AKC explains that young puppies tend to stay close, which can lull owners into thinking the training is solid. Once the puppy gains confidence, it may stop sticking close, and its lessons can seem to disappear.

A 2020 study in Biology Letters looked at this in guide dog puppies: Labrador and Golden Retrievers, German Shepherds and crosses. At 8 months, dogs were less likely to sit when their own carer asked than at 5 months, though they responded better to a stranger. Carers rated the dogs less trainable at 8 months, but by 12 months the scores were back up and higher than at 5 months.

The same study found separation-related behavior about 36% higher at 8 months than at 5 or 12 months. The authors note that age groups would need to be rethought for other breeds. So a Berner’s teen phase may not follow the same timing.

Physical maturity

The AKC says smaller dogs tend to mature faster than larger breeds, and that larger dogs may not reach physical maturity until 18 to 24 months. It also says growth plates in large and giant breeds close as late as 16 to 18 months. Our Bernese growth chart shows what’s known about how Berners grow, and where the data runs out.

The second and third years

For large dogs in general, the AKC’s large-breed guide says they’re slower to mature than small dogs. It says it can take months for a puppy to find its “off” switch, that the second year is much better, and that by age three most are calm, trustworthy pets.

That’s the closest thing to an age we found. It’s about large dogs as a group, not Berners.

Adulthood and beyond

A 2020 study in Frontiers in Veterinary Science surveyed owners of 1,207 adult dogs in Hungary. It found that activity and excitability went down with age. Dogs older than 3 scored lower than 1-to-3-year-olds, and the biggest drop came between those young adults and dogs aged 3 to 6.

Responsiveness to training told a different story. It scored highest in dogs aged 3 to 6, and only dogs over 12 scored clearly lower than the youngest adults.

That study mixed many breeds and didn’t single out Berners. It does suggest a dog’s energy keeps easing well past puppyhood.

Bernese Mountain Dog energy level by life stage

Putting the sources side by side gives a rough picture. Only the first and last rows rest on Berner-specific sources.

Is my Bernese Mountain Dog hyper, or just young?

A busy young Berner may simply be young, since the BMDCA says young dogs can be very active. But the club also points to a few things that can make any Berner harder to live with.

• Not enough exercise. The BMDCA says Berners are farm dogs by heritage and need exercise to stay fit in mind and body. A small yard, it says, is not enough on its own.
• Too much time alone. The same sheet says Berners don’t do well when cut off from people, and that behavior problems are likely when they’re denied plenty of time with their family.
• Not enough training. The club’s FAQ links the calm adult directly to training.

Big-puppy manners

A bouncy Berner puppy is a lot of dog to greet. The club’s training sheet suggests recruiting visitors to reward your puppy gently for sitting or keeping “four paws on the floor,” and for taking treats softly. To protect small fingers, it suggests having young children put the treat on the ground.

When to call your vet

If your dog’s behavior changes suddenly, or it seems restless, sore or unwell, ask your vet. A sudden change is worth a checkup.

How to help your Berner settle

You can’t rush maturity, but you can shape the dog that comes out the other side.

Start training early and keep it positive

The BMDCA’s About Bernese Mountain Dogs sheet recommends a puppy kindergarten class between four and six months, then a first-level obedience course before the first birthday. It says all training should use positive methods. The FAQ adds that most Berners are sensitive, and bad or scary experiences are hard to undo.

The club’s training sheet suggests 15 minutes of focused socialization twice a day if you’re working on your own. Our guide to Bernese puppy training covers the first eight weeks at home, and Bernese Mountain Dog training picks up with leash manners and recall.

Stay consistent through the teen months

The AKC advises keeping up obedience practice several times a week and rewarding good choices. It suggests mental work like puzzle toys and trick training for teens with lots of energy, and teaching “leave it” and “drop it” to build self-control.

Exercise that suits a growing body

A tired puppy is easier to live with, but growing joints need care. The BMDCA says puppy exercise should never be forced, like jogging or long rough play. See how much exercise a Bernese puppy needs for safe ways to burn energy.

Spay or neuter: a medical decision first

The BMDCA says spayed and neutered dogs generally avoid some mating-related behaviors, such as excitability around the opposite sex, marking and roaming. It also notes growing evidence that waiting may have health benefits. Read when to spay or neuter a Bernese, and make the timing decision with your vet.

Get help early

If worrying behavior shows up, the club’s training sheet suggests contacting your dog’s breeder and a professional trainer or animal behaviorist. Ask your vet too, especially if the change is sudden.

What a calm adult Berner looks like

The payoff is worth the wait. The BMDCA describes adult Berners as gentle, easygoing and tolerant, and not prone to barking too much unless left alone too long. The breed standard calls for a self-confident, alert, good-natured dog that may stay aloof with strangers.

For more on the adult personality, read Bernese Mountain Dog temperament. If you have kids, see are Bernese good with kids. For the whole first year, start with our guide to Bernese Mountain Dog puppies.