A dog grips a rope toy and leans back, growling happily. Its owner pulls, and the dog pulls harder. It feels enormous. But how much force is really going through those teeth?
No scientist has published a bite-force measurement for a pit bull breed, so the famous “235 psi” figure has no study behind it. Real dog studies give the best guide: awake pet dogs averaged 256 newtons (about 58 pounds of force) [1], and the one pit bull–shepherd cross ever tested under anaesthesia bit 896 N (201 lbf) at its fangs [2].
Key takeaways
- No breed measurement: we found no published study that measured the bite of a pit bull breed. The “235 psi” figure traces back to a TV programme, not a paper.
- Real dog bites: 22 awake pet dogs bit 13–1,394 N, averaging 256 N [1]. Dogs under anaesthesia bit 147–946 N at the fangs and 524–3,417 N at the back teeth [2].
- Size matters most: heavier dogs bite harder [2][3], so a big dog of any breed usually out-bites a smaller one.
- “Psi” is the wrong unit: bite sensors measure force (newtons or pounds of force), not pressure.
- No locking jaws: a dog’s jaw is a hinge closed by muscles [4]. Holding on is behaviour, not a lock.
How strong is a pit bull’s bite?
Nobody knows exactly, because no study has measured a group of pit bulls. The closest data point is a single 24 kg female, recorded as a “Pit Bull–Shepherd cross”, in a 2008 University of Guelph study. Under anaesthesia, with its jaw muscles stimulated, it bit 896 N (201 lbf) at the fangs and 1,991 N (448 lbf) at the back teeth [2].
That one dog is useful, but it is not a breed average. Its breed was estimated by eye, and stimulated bites are not the same as a dog choosing to bite. Its fang bite was the second highest of the 20 dogs tested, while its back-tooth bite sat in the middle of the group. Heavier dogs in the same study, like a 40 kg Labrador–shepherd cross, bit harder at the back teeth: up to 3,417 N [2].
What do real dog bite-force studies show?
Only a handful of teams have measured dog bites. A 1995 University of Illinois team built a force transducer covered in rawhide and recorded 101 bites from 22 pet dogs of 7–55 kg. Bites ranged from 13 to 1,394 N, with a mean of 256 N and a median of 163 N. Most were gentle: 77% were under 400 N [1].
A veterinary review of that study notes that the dogs’ bite force rose only slightly with body weight. The biggest factor was how keen each dog was to chew the sensor [4]. The 2008 Guelph study removed that problem by stimulating the jaw muscles of 20 dogs (5–40 kg) under anaesthesia. Forces were 147–946 N at the canine teeth and 524–3,417 N at the second molar. Once one unusual dog was set aside, body weight alone explained 88% of the variation in back-tooth bite force [2].
A 2009 study of 127 dog skulls by the same team found that predicted bite force rises with size. Skull shape also mattered in medium and large dogs, but not in small ones [3]. And in 2021, Finnish researchers measured police dogs biting a padded sleeve fitted with force sensors: German shepherds had a median of 360 N and Belgian Malinois 247 N [5].
Measured dog bites vs human and wolf
Bite force in newtons (pounds of force in brackets). Bars are drawn to scale against the strongest dog bite measured. The pale bar is a skull-model estimate, not a measurement.
Strongest dog, back teeth (40 kg, under anaesthesia): 3,417 N (768 lbf)
Pit bull–shepherd cross, back teeth (one 24 kg dog): 1,991 N (448 lbf)
Strongest awake pet dog (of 22): 1,394 N (313 lbf)
Adult human (typical maximum bite range): 446–1,221 N (100–274 lbf)
Pit bull–shepherd cross, fangs (one 24 kg dog): 896 N (201 lbf)
Grey wolf, fangs (35 kg, skull-model estimate): 593 N (133 lbf)
German shepherd police dogs, sleeve bite (median of 6): 360 N (81 lbf)
Average awake pet dog bite: 256 N (58 lbf)
Sources: Ellis et al. 2008 [2]; Lindner et al. 1995 [1]; Koc et al. 2010 [6]; Wroe et al. 2005 [7]; Hyytiäinen et al. 2021 [5]. Pounds of force are our conversions (1 lbf = 4.448 N). Methods differ between studies, so compare bars with care.
Why is “pit bull bite force psi” the wrong question?
Psi (pounds per square inch) measures pressure, which is force divided by contact area. Bite sensors measure force. The same bite gives a huge “psi” through a sharp fang tip and a small one through a flat back tooth, so one psi number for a whole dog is meaningless unless the tooth and contact area are stated. Viral lists never state them.
Most “psi” bite figures online are probably forces in pounds with the wrong label, the same mix-up our animal bite force rankings found for crocodiles and hyenas. Real tooth pressures are much higher than 235 psi anyway: in the police-dog study, the pressure under single teeth went off the top of the sensors’ 300 N/cm² scale [5], which is about 435 psi (our conversion).
Where does “235 psi” come from?
Most websites credit it to a National Geographic TV programme presented by the reptile expert Brady Barr in the mid-2000s. A Dangerous Encounters episode called “Bite Force” is listed as first airing in May 2005, and its listing describes a Nile crocodile test [8]. We could not find a published study, a methods description or a sample size for any dog figures from it.
| Popular claim | What we found | Verdict |
|---|---|---|
| Pit bull “235 psi” (sometimes “242”) | Credited online to Brady Barr’s National Geographic TV work. No paper, method or sample size found. Read as pounds of force, 235 lbf is about 1,045 N, inside the range real dogs bite [1][2] | TV figure, untraceable, likely force with the wrong unit |
| Rottweiler “328 psi”, German shepherd “238 psi” | Same lists, same uncited source. The only published German shepherd measurements are police dogs biting a sleeve, median 360 N (81 lbf) [5] | No primary source found |
| Kangal “743 psi” | No study found. As a force, 743 lbf is about 3,305 N at the front teeth, 2.4 times the strongest bite recorded from 22 awake pet dogs [1] | No source |
| “An AVMA study found pit bulls bite no harder than other dogs” | The AVMA’s 2014 literature review on breed and bite risk does not discuss bite force at all [9] | Misattributed |
| “A Journal of Applied Animal Welfare Science study measured 235 psi” | We found no such study. The pit bull-related paper we found in that journal compares shelter breed labels with DNA results [10] | No such study found |
Is a pit bull’s bite stronger than a German shepherd’s or a Rottweiler’s?
No study has tested these breeds side by side, so nobody can say. The one pit bull–shepherd cross was tested under anaesthesia [2], while the German shepherds were police dogs biting a sleeve [5]. Those methods are too different to compare. What the science does show is that bigger dogs tend to bite harder [2][3].
So the honest answer is that a heavier dog of any of these breeds will usually out-bite a lighter one. Individual dogs still vary: one dog in the 2008 study bit so much less than expected for its weight that the researchers treated it as an outlier [2]. For a bigger mastiff-type breed, see our cane corso bite force estimate, built from the same studies.
Do pit bulls bite harder than wolves?
There is no fair comparison yet. No wild wolf’s bite has been measured with a sensor in a published study that we found. A 2005 skull model estimated 593 N (133 lbf) at a 35 kg grey wolf’s fangs [7]. But the 2008 dog study found that such lever models gave only 39–61% of the force dogs really produced [2], so the wolf’s true bite is probably higher.
What the model does show is that wolves bite hard for their size. Their “bite force quotient”, which compares bite with body weight (100 is average), was 136, among the highest of living dog-family members [7]. Read more in our guide to wolf adaptations.
Picture it: how hard is a dog’s bite?
- The average pet-dog bite is like a heavy sack. 256 N ÷ 9.81 ≈ 26 kg. That is like a 26 kg sack resting on the dog’s teeth.
- The pit bull cross’s fang bite is like an adult standing on it. 896 N ÷ 9.81 ≈ 91 kg, the weight of a large adult.
- Same bite, very different “psi”. 1,000 N on 1 cm² is 10 million pascals, or about 1,450 psi (10,000,000 ÷ 6,895). Spread over 10 cm², it is about 145 psi. Nothing about the bite changed, only the area.
- A crocodile beats a dog about 12 times over. The record saltwater crocodile bit 16,414 N [11] (more in our alligator vs crocodile guide). 16,414 ÷ 1,394 (the strongest awake pet dog) ≈ 11.8.
Calculations are ours, using the figures above. 1 kg weighs about 9.81 N; 1 psi is about 6,895 pascals.
Are pit bull bites more dangerous?
The evidence is mixed. An American Veterinary Medical Association (AVMA) review found pit bull-type dogs are identified more often in the small number of very severe or fatal attacks. It also warned this may reflect how common the dogs are locally, reporting bias and how owners treat them, and said controlled studies have not found the group disproportionately dangerous [9].
Other studies point the other way on severity. A 2019 review of facial dog bites, combining hospital records with a literature search, found injuries from pit bulls and mixed-breed dogs were both more frequent and more severe [12]. Larger dogs of any breed are involved in more attacks on people, the AVMA review notes [9].
One big problem runs through all of this: breed labels are often wrong. When shelter staff in Florida judged 120 dogs by eye, they called 52% of them pit bull-type, but DNA tests identified only 21% [13]. In a study of 256 US dog bite-related deaths from 2000 to 2009, a valid breed could be determined in only 17.6% of cases. The researchers found that four or more preventable factors, such as no able-bodied person present to intervene, co-occurred in 80.5% of deaths, and breed was not one of these factors [14].
The AVMA review’s conclusion is that breed is a poor sole predictor of aggressiveness [9]. Bite force tells you what a jaw can do, not what a dog will do.
How can you prevent dog bites?
The US Centers for Disease Control and Prevention (CDC) says most dog bites are preventable [15]. Its advice works for every breed:
- Always supervise children while they play with dogs, even dogs they have met before [15].
- Ask the owner before you pet someone else’s dog [15].
- Never encourage a dog to play aggressively or roughhouse [15].
- Around a dog you don’t know, avoid panicking, loud noises and running [15].
If someone is bitten, the UK’s NHS advises cleaning the wound with soap and warm water, and going to A&E if the wound is large or deep or the bleeding will not stop [16]. Follow your own local health service’s advice. This section is general safety information, not medical or veterinary advice.
Myths about pit bull bites
Myth: Pit bulls have locking jaws.
Fact: No dog does. A 2018 veterinary review describes the dog’s jaw joint as moving mainly in a hinge-like up-and-down motion, closed by the temporal, masseter and pterygoid muscles [4]. Nothing in that anatomy works like a lock. A dog that keeps hold is using muscle and motivation. Why people believe it: some dogs grip hard and hang on, which looks like a lock from the outside.
Myth: Pit bulls have the strongest bite of any dog, at 235 psi.
Fact: No study has measured pit bull breeds, and the 235 figure has no published source. Even the viral lists that use it put the pit bull below the Rottweiler and German shepherd. In real studies, body weight is the best predictor of a dog’s bite [2][3]. Why people believe it: pit bull-type dogs are muscular and broad-headed, so a big number sounds right.
Myth: A stronger bite means a more dangerous dog.
Fact: Bite force is a measure of the jaw, not of temperament. The AVMA review lists training method, sex and neutering status, the target and the setting as factors that stop breed from predicting aggression on its own [9]. Why people believe it: strength and danger feel like the same thing.
From wolf to pet: why dogs have the bite they do
Dogs were the first domestic animal. A 2020 study of 27 ancient dog genomes found that all dogs share an ancestry distinct from today’s wolves, and that at least five major dog lineages already existed 11,000 years ago [17]. Their wild relatives still need a strong bite for their place in nature. Grey wolves are hypercarnivores that often hunt animals larger than themselves, and that is linked to their high bite force for their size [7]. A pet dog’s food comes from people, so its jaws mostly grip toys and chews instead. Its bite is a family heirloom from those ancient wolves.
Test yourself
1. Has anyone measured the bite force of a pit bull breed in a published study?
No. The closest is one 24 kg “Pit Bull–Shepherd cross” tested under anaesthesia: 896 N at the fangs and 1,991 N at the back teeth.
2. What best predicts how hard a dog can bite?
Body size. Heavier dogs bite harder, and in one study body weight explained 88% of the variation in back-tooth bite force.
3. Do pit bulls have locking jaws?
No. A dog’s jaw is a hinge worked by muscles, with no locking part.
Where to next?
⬆️ Go wider: which animal has the strongest bite force, ranked➡️ Go deeper: cane corso bite force, what the dog studies really show🔀 Go sideways: wolf adaptations, from jaws to teamwork
Frequently asked questions
What is the bite force of a pit bull in psi?
There is no measured psi figure for any pit bull breed, and psi is the wrong unit for bite force. The popular “235 psi” has no published study behind it. The only pit bull-type dog we found in a study, a pit bull–shepherd cross, bit 896 N (201 lbf) at its fangs under anaesthesia.
How much bite force does an American pit bull terrier have?
No one has published a measurement for the American pit bull terrier. Based on studies of mixed dogs, our rough estimate is that a healthy adult of pit bull size can bite with several hundred newtons at the front teeth and more at the back teeth, but individual dogs vary widely.
Which dog breed has the strongest bite?
Nobody knows, because no study has compared breeds head to head. The “Kangal 743 psi” claim has no source we could find. Studies show bigger, heavier dogs usually bite hardest.
Is a pit bull bite stronger than a human bite?
Probably, but not by as much as people think. Studies with bite sensors find adult humans bite with a maximum of about 446–1,221 N [6]. For more human-vs-animal numbers, see you vs a chimpanzee. The pit bull–shepherd cross bit 1,991 N at its back teeth under anaesthesia.
Can a pit bull lock its jaws?
No. A dog’s jaw moves like a hinge and is closed by muscles. There is no locking mechanism in any breed.
Sources
- Lindner, D.L., Marretta, S.M., Pijanowski, G.J., Johnson, A.L. and Smith, C.W. (1995). Measurement of bite force in dogs: a pilot study. Journal of Veterinary Dentistry 12(2): 49–52.
- Ellis, J.L., Thomason, J.J., Kebreab, E. and France, J. (2008). Calibration of estimated biting forces in domestic canids: comparison of post-mortem and in vivo measurements. Journal of Anatomy 212(6): 769–780. Per-dog data in Tables 1 and 3.
- Ellis, J.L., Thomason, J., Kebreab, E., Zubair, K. and France, J. (2009). Cranial dimensions and forces of biting in the domestic dog. Journal of Anatomy 214(3): 362–373.
- Kim, S.E., Arzi, B., Garcia, T.C. and Verstraete, F.J.M. (2018). Bite forces and their measurement in dogs and cats. Frontiers in Veterinary Science 5: 76.
- Hyytiäinen, H.K., Blomvall, L., Hautala, M. and Lappalainen, A.K. (2021). Reliability of a new bite force measure and biomechanics of modified long attack in police dogs. Animals 11(3): 874.
- Koc, D., Dogan, A. and Bek, B. (2010). Bite force and influential factors on bite force measurements: a literature review. European Journal of Dentistry 4(2): 223–232.
- Wroe, S., McHenry, C. and Thomason, J. (2005). Bite club: comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa. Proceedings of the Royal Society B 272: 619–625.
- TheTVDB. Dangerous Encounters episode list (“Bite Force”, first aired 27 May 2005). Cited only to show where the TV figure circulates.
- American Veterinary Medical Association, Animal Welfare Division (2014). Literature review: the role of breed in dog bite risk and prevention. Read via the February 2024 web.archive.org copy, as the live page blocked automated access.
- Voith, V.L., Ingram, E., Mitsouras, K. and Irizarry, K. (2009). Comparison of adoption agency breed identification and DNA breed identification of dogs. Journal of Applied Animal Welfare Science 12(3): 253–262.
- Erickson, G.M. et al. (2012). Insights into the ecology and evolutionary success of crocodilians revealed through bite-force and tooth-pressure experimentation. PLOS ONE 7(3): e31781.
- Essig, G.F. Jr, Sheehan, C., Rikhi, S., Elmaraghy, C.A. and Christophel, J.J. (2019). Dog bite injuries to the face: is there risk with breed ownership? A systematic review with meta-analysis. International Journal of Pediatric Otorhinolaryngology 117: 182–188.
- Olson, K.R., Levy, J.K., Norby, B. et al. (2015). Inconsistent identification of pit bull-type dogs by shelter staff. The Veterinary Journal 206(2): 197–202.
- Patronek, G.J., Sacks, J.J., Delise, K.M., Cleary, D.V. and Marder, A.R. (2013). Co-occurrence of potentially preventable factors in 256 dog bite-related fatalities in the United States (2000–2009). Journal of the American Veterinary Medical Association 243(12): 1726–1736.
- Centers for Disease Control and Prevention (2026). Dogs: healthy pets, healthy people. Dog bite prevention advice.
- NHS (reviewed 27 October 2025). Animal and human bites.
- Bergström, A. et al. (2020). Origins and genetic legacy of prehistoric dogs. Science 370(6516): 557–564.
Corrections: on 14 October 2026 we rewrote this article. The earlier version cited an “AVMA study” and a Journal of Applied Animal Welfare Science study on pit bull bite force that we could not find, gave unsourced “psi” figures (235, 305, 238–328, 743 and “300–700 psi” for dogs in general) and mixed up force with pressure. Those claims have been corrected or removed.
Sources checked 14 October 2026.
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