The topic of pepper spray or mace strength is often a confusing and misinterpreted subject. There are two common inaccurate measures of pepper spray strength and one true indicator of strength.
The one correct indicator of pepper spray potency, as recognized by the EPA & US Federal Government, is Major Capsaicinoids (MC). MC represents the strength of the entire formulation within your pepper spray. Typical sprays range from 0.18 to 1.33% MC. The higher the MC of the pepper spray the greater the potency. Sprays with higher MC are more effective as well. A good example, Gasoline, is typically 87, 89 or 91 Octane. The higher the gasoline’s octane rating, the greater the fuels performance. Proof, another example, is the measure of liquor strength. The higher the proof, the stronger the liquor.
Bear Attack Deterrent Sprays measure between 1.0% and 2.0% Major Capsaicinoids.
The two inaccurate measures of pepper spray strength are Oleoresin Capsicum percentages (OC%) & Scoville Heat Units (SHUs). Pepper sprays contains anywhere from 2-10% OC, but OC% only measures the amount of raw pepper or Oleoresin Capsicum (OC) within the pepper spray formulation. The OC% does not take into account the actual potency of that OC. SHUs are an inaccurate measure because they only measure the strength of the previously mentioned raw OC, which is then diluted from 90 to 98% because OC only measures between 2-10% of the formulation. Here is an example of how SHU can be misleading: a 5.3 Million SHU spray with 2% OC measures only 0.71% MC. while a 2 Million SHU spray with 10% OC measures 1.33% MC. Which spray is more potent? The 1.33 MC pepper spray is nearly twice the strength.
So when purchasing pepper spray, remember major capsaicinoids equals strength!