NotABully.org is reader-supported. We may earn a small commission through products purchased using links on this page.
The group of breeds often collectively referred to as Pitbulls has unfortunately been mischaracterized for years by myths and erroneous “breed facts.”
Specifically, many of these misconceptions revolve around Pitbull bites, suggesting that they have extremely strong bites, that they can “lock” their jaws, or that they are more prone to bite or kill than other breeds – none of which are true.
In fact, bite strength is actually better indicated by the overall size of the dog rather than by breed, as we’ll discuss more in-depth later.
So, how strong is a Pitbull’s bite?
On average, Pitbull-type dogs have a bite strength of around 235 pounds per square inch (PSI). This is consistent with the bite strength of other dog breeds in the same size/weight class, and it’s a considerably lower bite force than that which many larger dog breeds exhibited in testing.
However, bite strength is a tricky thing to measure accurately, and there are many factors that can impact the force of a dog’s bite at any given time, which we’ll review shortly. We’ll also do a little myth busting and put a Pitbull’s bite force into an easier-to-understand context.
Let’s dive in!
How is Bite Force Measured?
First, it’s important to understand how bite force is measured, both in terms of units of force and in the practical and theoretical assessment of the force. That sounds complicated, but don’t worry – this won’t turn into a physics class!
PSI vs. Newtons
PSI and newtons are both units used to describe force or pressure. Sometimes they are incorrectly used interchangeably without accounting for the conversion rate, which may have caused some of the misinformation about Pitbull bites in the first place.
Pounds per square inch, or PSI, is the pressure rating with which most Americans are familiar, since it’s part of the avoirdupois (non-metric) system of measurements. A PSI rating will tell you, as the name indicates, how much pressure in pounds is being exerted on a surface that measures one square inch.
The measurement is commonly used for everyday tasks like inflating car tires to the proper air pressure, but it can also be used to quantify the force exerted by a dog’s jaws.
Newtons, on the other hand, are part of the International System of Units (the modern metric system, commonly abbreviated as SI). Newtons describe force in a slightly different way: one newton is equal to the force necessary to cause one kilogram of mass to accelerate at a rate of one meter per second squared.
I know, my head is spinning too.
Basically, it’s the force needed to create a change in velocity over time – representing an increase in the rate of movement of one meter per second, every second.
Conveniently, PSI can be converted into newtons and vice versa: 1 newton is equal to a pound-force or PSI of about 0.22. So, our average Pitbull bite strength of 235 PSI could also be presented as 1,045.33 newtons.
Now that we’ve set ourselves up for success with the correct units and their conversion rate, let’s move on to how bite force is actually assessed and measured.
Theoretical vs. Practical Measurements
Researchers have used four main methods to try to measure bite strength in various studies: geometrical analysis of dog skulls, electrical stimulation of jaw muscles in anesthetized dogs, placement of electrodes on dogs’ jaws while they chew, and using a transducer (a device that measures force) that’s wrapped in a tasty treat.
All of these methods have their own pros and cons.
For example, the geometrical analysis method attempts to find the theoretical maximum force that could be applied by a dog’s jaws, which is useful information no doubt, but isn’t particularly practical since in a real-world situation a dog is almost certainly never going to apply the absolute maximum pressure – it would likely result in torn jaw muscles, broken teeth, and/or perhaps even a broken jaw.
The electrode method is similarly flawed in that the unconscious dogs were not concerned with preserving their teeth, jaws, and jaw muscles, so the measured forces are also likely unrealistically high. Side note: this sounds like an inhumane study but the dogs were all scheduled for humane euthanasia for unrelated reasons and were euthanized immediately following the anesthetized study.
Conversely, the electrodes and treat-wrapped transducer are likely to generate unrealistically low estimations of bite force, since the dogs were all awake and leisurely chewing food rather than attacking or defending themselves with a bite.
Different Force in Different Parts of the Mouth
Further complicating the measurement process is the fact that different forces are exerted at different parts of the jaw. Many studies account for this by measuring force at both the molars and the canine teeth and averaging the findings.
In one case, a German Shepherd exerted a 170 PSI force with its front teeth while its molars generated a force of 568 PSI, demonstrating how the lever principle results in stronger forces nearer the fulcrum – which, for our purposes, is where a dog’s upper and lower jaws hinge together.
The Bottom Line: It’s Hard To Accurately Measure Bite Force In Pitbulls
As you can see, it’s nearly impossible to measure bite force in a practical sense, because we can’t just ask a Pitbull to hold a transducer in his jaws and bite down as hard as he can without hurting himself. Maybe one day…
For now, we’ll have to rely on imperfect measurement techniques and keep in mind that there are a whole host of components that can impact how hard a Pitbull (or any dog) can or will bite.
Factors That Affect A Pitbull’s Bite Force
Many different internal and external factors contribute to the actual (as opposed to theoretical) force of a pitbull’s bite.
Bite force in dogs is strongly correlated with body weight, which is in fact the number one indicator of canine bite strength. According to all the studies we’ve referenced so far, there is no correlation between specific breeds and bite strength.
There can be quite a bit of variation in size and weight between members of the same breed, and especially within the Pitbull family of breeds. Pitbull-type dogs can weigh anywhere from around 30 pounds to upwards of 90 pounds! As you can imagine, a petite 30-pound Pitbull will likely have a significantly less strong bite than one three times her size.
So, it’s important to note that although we mentioned earlier that Pitbulls have a bite force of around 235 PSI, it is indeed an average and an estimate – not an exact measurement for all Pitbull-type dogs.
And, of course, if a Pitbull is obese, he will not have any extra biting power over a healthy-weight Pitbull of the same build.
So as a general rule: the bigger the Pitbull, the stronger the bite.
Skull Shape and Size
The measurements and shape of the skull and jaws are also correlated somewhat with bite strength, although only in medium and large dogs. So, if you have two dogs of the same weight, you can place your bets on which can bite harder based on which has the bigger head and wider jaws.
Since Pitbulls are known for their big adorable blockheads and wide smiles, they will generally have a stronger bite than a dog of another breed that’s the same weight but has a smaller head and narrower jaw.
Condition of Jaws and Teeth
Naturally, if a Pitbull experiences pain in his jaws or teeth when he bites down, he’s less likely to bite hard. Medical conditions like tooth decay, TMJ disorders, jaw muscle atrophy, and misaligned teeth can all cause a dog to avoid biting at maximum strength.
Training can also play a huge role in whether a dog will bite at all, and if he does, how hard he bites. Pitbulls who have been taught bite inhibition as puppies are less likely to bite as adults and they can be more mindful of the force they are applying with their jaws.
Motivation and the Situation
If you were chewing something soft like oatmeal, you wouldn’t go at it with nearly the same vigor or force that you would use on a strip of beef jerky. PItbulls are the same way – they are only going to bite with as much force as they deem necessary for the situation.
This is exactly why it’s hard to measure bite force accurately in dogs who are awake: how do you motivate a dog to bite as hard as he can while not breaching any ethical boundaries?
In a real world situation where a dog feels threatened or is in pain he’s much more highly motivated to bite the threat hard, compared to casually chomping on a snack in the lab.
The Individual Dog
Finally, bite force can come down to the temperament of an individual dog and the training he has received. Frankly, some dog are just more easily irritated than others and may react more aggressively.
Mythbusters: Pitbull Edition
Whew, now that we’ve gotten all the science background information out of the way, let’s look at how these facts apply specifically to Pitties by busting some myths about the breed.
Myth #1: Pitbulls Have Locking Jaws
False. Pitbulls have the same exact jaw structure as all other dogs – the only difference between breeds is the size and shape of the jaws. As Dr. Tracy Fanara demonstrates, there are no jaw-locking mechanisms present on a Pitbull’s x-ray:
One reason that this myth may have been perpetuated is that Pitbulls can bite and hang on seemingly forever, such as when they are playing tug-o-war. However, this isn’t a behavior unique to Pitties (dogs of all breeds can and will do this) and it generally just indicates dedication to winning the game of tug!
Myth #2: Pitbulls Have the Strongest Bite
False. Mastiffs have the strongest bite of all dogs (that have been officially measured to date), exerting an impressive 552 PSI. The Pitbull’s average bite force is less than half as strong. Not-so-incidentally, Mastiffs have the highest body weight, largest heads, and widest jaws of all dog breeds.
Pitbulls have a bite force that’s to be expected for any breed in their size and weight class, and many larger breeds can bite with significantly more force, including Rottweilers and German Shepherds.
For reference, humans have a bite strength of around 120 PSI, lions and sharks clock 600 PSI, hyenas come in high on the list with 1,000 PSI, and Nile alligators completely crush (literally) the competition with a bite strength of almost 2,500 PSI. Moral of the story? You should be much more concerned about getting chomped by an alligator than by a Pittie!
I’ll say it again for those in the back: bite strength is correlated to overall body weight, head size, and jaw width – it’s not correlated to specific breeds. In the dog kingdom, Pitbull-type dogs are generally in the medium range of the size spectrum (with some exceptions of course). Therefore, they aren’t even close to having the strongest bite.
Myth #3: Pitbulls are More Likely to Bite In General
False. The American Veterinary Medical Association Animal Welfare Division states that Pitbull-type dogs are not implicated in controlled studies as being disproportionately dangerous. Pitbulls were highly identified in biting incidents, but so were Spaniels, Jack Russell Terriers, and Labs – none of which would likely be considered “dangerous” breeds by the general public.
The AVMA notes that some aggressive dogs may also be misidentified as Pitbulls, due to the fact that the term “Pitbull” actually refers to a loosely defined collection of breeds and ambiguous physical characteristics. The stigma surrounding the breed may lead some people to identify a biting dog as a Pitbull regardless of its actual breed.
Furthermore, the AVMA indicates that prevalence of a breed within a community can play a role in how often it is implicated in biting incidents. As an example, they noted that in some parts of Canada, Siberian Huskies and other sled dogs are responsible for the most fatal dog attacks of any breed due to their high prevalence in the area.
The bottom line is that predictions about aggressive behavior and likelihood of biting can’t be made based on breed.
Myth #4: Pitbull Bites are More Likely to Be Severe or Fatal
False. A study in Ireland looked at this exact issue and found that for both the type of bite inflicted and the medical care required, there was not a significant difference between legislated dogs (i.e. Pitbulls and other “banned” breeds) and non-legislated breeds.
Additionally, the Center for Disease Control (CDC) conducted a study that found that over 70% of dog bite fatalities in humans are caused by breeds other than Pitbull-type dogs. The AVMA also points out this information cannot accurately be used to infer the “dangerousness” of any breed since that would require the inclusion of the total numbers of each breed of dog living in the United States for each year of the study, and that information is not available.
Finally, fatal dog bites are exceedingly rare overall and should not be used as a means of discriminating against any one breed.
Myth #5: Breed-Specific Legislation (BSL) Against Pitbulls is Effective
False. Numerous studies in countries around the world have found that BSL is not effective as a means of reducing dog bite incidents. For example, there are studies from Ireland, Canada, and the Netherlands among many others. Despite that, there are still many places around the world that have banned all Pitbull-type dogs.
It has actually been found that breed-neutral legislation (such as requiring dog licenses and ticketing for infractions) is more effective at reducing dog bites.
Hundreds of years ago, Pitbulls were initially bred to fight, bait bulls, and hunt hogs, and many people have not accepted that breed standards and purposes can change and evolve over time. At this point, the stigma is almost more associated with the word “Pitbull” than it is with any actual dog – read about our experiment with this phenomenon here.
Fortunately, as more and more studies disprove these myths about Pitbulls, we can advocate for our beloved meatballs with facts and science to fight back against breed discrimination!