Rule of thumb: 1 security officer per 75-150 visitors, depending on risk level. Open bars (higher risk): 1 per 75. Business conference: 1 per 150. Outdoors or at night: lower ratio. The number counts, but so do positioning and training. Two security officers are enough for 150 calm attendees; ten are not enough for 150 energetic festival-goers. Live Impact calculates the requirement per scenario.