How hard is a zombie's head?

This is a good question for potential zombie hunters to consider and the representations presented in pop culture tend to vary quite a bit. In show's like AMC's The Walking Dead, the skulls of walkers seem to be pretty soft with characters crushing them at will with seemingly no difficulty. But how accurate is that? The truth is, skull strength will vary from zombie to zombie and could be dependent in large part on the age and health of the person who became the zombie. In young children the skull is relatively soft as the bones of the skull have not fully formed and fused. In the case of the elderly, the bones might have become brittle. In medical terms this is called low bone density. A study conducted by researchers at Tianjin University of Science and Technology in China found the average thickness of a male skull was 0.25 inches (6.5 millimeters), while the average thickness of a female skull was 0.28 inches (7.1 millimeters). Skulls are thinner on the sides that front and rear. Given the variables in density and thickness, it's difficult to say just how hard an “average” head is. However, experts in combat and human anatomy place an average force of 81 psi to create a skull fracture. While this amount might be hard for a person to achieve with their bare hands, it is quite possible using a lever. The lever, whether a simple bat or club or something edged like an axe, multiplies the force of a person's swing. The impact force is calculated using the formula E = 1/2 m v². So, could you punch a zombies skull in? Not very likely. However, with a good bat – or better yet a trucker's friend – you could easily get the job done.