Bite force measures the maximum pressure generated by jaw muscles when the teeth clamp down. This pressure depends on muscle strength, jaw mechanics, and the contact area of the teeth. For the average adult, this maximum force ranges between 160 and 200 pounds per square inch (PSI). In metric units, this translates to approximately 720 Newtons. This force is adequate for chewing a wide variety of foods, reflecting the human omnivorous diet.
Quantifying Human Bite Force
Jaw force is quantified using standardized metrics, primarily Pounds per Square Inch (PSI) and Newtons (N). PSI measures pressure distributed over an area, while Newtons measure the force itself. Scientists use a specialized device called a gnathodynamometer to measure this maximum force in a laboratory setting.
It is important to distinguish between maximum force and the functional force used for daily chewing. The maximum bite force for a healthy adult can range widely, from about 285 to 700 Newtons, depending on the individual. However, the force used during normal chewing is significantly lower, typically falling between 100 and 150 Newtons.
The location where the bite is measured dramatically affects the reading due to mechanical leverage. Force is concentrated in the molars, which are positioned closer to the temporomandibular joint (TMJ), acting as the jaw’s fulcrum. As a result, molars generate a much higher force than the incisors, which are farther away. This mechanical advantage allows the rear teeth to perform the grinding necessary to break down tougher foods.
Biological Factors Influencing Bite Strength
The strength of a human bite is determined by several anatomical and physiological variables. The most influential factors are the size and contractile strength of the main muscles of mastication, particularly the masseter and temporalis muscles. Larger, denser muscles generate more pressure than smaller ones.
The architecture of the jawbone, known as craniofacial morphology, plays a significant role by affecting leverage. Individuals with a “short-faced” structure, characterized by a compact jaw, often exhibit stronger bite forces due to thicker, more efficient masseter muscles. In contrast, a longer, narrower facial structure reduces the mechanical advantage of the jaw muscles.
The health of the temporomandibular joint (TMJ), which connects the jawbone to the skull, directly influences the maximum force a person can exert. Pain or dysfunction in the TMJ can cause individuals to limit their biting effort, leading to a reduction in maximum bite force. Non-modifiable factors such as age and gender also contribute to variations. Bite force tends to peak in early adulthood and is higher in males due to greater average muscle mass.
How Human Bite Power Compares to the Animal Kingdom
The average human bite force (160 to 200 PSI) is substantial for human needs but is modest compared to many animals. Even relatively close primate relatives exert significantly more force. For example, a gorilla’s bite force can reach an estimated 1,300 PSI, necessary for its diet of tough, fibrous plants.
Carnivores possess immense bite power designed for crushing bone and tearing flesh. The spotted hyena, known for its bone-crushing capabilities, can bite with a force of around 1,100 PSI. Even the average domestic dog exhibits a stronger bite than a human, with forces ranging from 200 to 300 PSI.
The strongest bites in the animal kingdom belong to large reptiles, whose jaws are built for maximal crushing force. The saltwater crocodile is recognized as the champion, capable of generating forces over 3,700 PSI. This difference highlights that the human jaw evolved for precision and versatility in processing cooked and prepared food, rather than for raw crushing power.