What's an ideal ratio of guests to security staff?

Q: Is there a ratio of guests to security people for a dance club that creates an ideal situation of good, safe fun?

A: Here is a question that will draw many different answers. I encounter this question with every project. The answer is simple: No two venues will have, or require, the same amount of security. It depends on many variables and factors with your venue. At all venues, safety and security is and should be top priority and is a must, especially for legal and liability purposes/reasons. An operator must provide a safe environment on your entire property, both inside and outside of your club/venue.
You must know your patron demographics. If I have a hip-hop dance club of 500 patrons in one room and the same club on another night with 500 dance/electronic music patrons, it’s likely that there are two different requirements for security.
Your best bet may be to consult a nightlife or security consultant to review your club and demographic.
In addition to patrons’ demographics, other variables to consider include line of sight coverage and room coverage. Every room or area of a venue occupied by patrons must have eyes on it; even if it is not dedicated security, a staff member must have observation of that area and must have direct communication with security at all times via radio. With a tough economy, security is a major overhead cost and many operators tend to cut back. If you are one of them, do make sure you have a proper contingency staff.
And remember, you must have proper coverage outside of your venue as well as inside. The extent of that coverage depends on your parking lot size and/or property. You are liable for the safety of your patrons on your property, period.
Still, there must be a rule of thumb answer to the question, and here it is:
For normal club operations, the rule of thumb is a security person outside your venue and in every main room and/or area. In a large room, the rule of thumb is one security staff to 100 patrons. (Normal operations means your regular crowd of patrons, in which the social dynamic is static and your crowd usually polices itself as most of your patrons are regulars, etc.)
For special events or non-routine club operations, etc., you should always have more security. Depending on the risk factor, one security guard to every 50 - 75 patrons is a rule of thumb. Especially for urban or hip-hop demographic you must follow the protocol for this scenario. Note: The social dynamic to special events is that there are many new faces and groups in your venue, so there will be more friction, as we are territorial by nature. We must be realistic and say that disputes are more likely to occur during special events/concerts/shows.
Remember there is common sense to deciding on security. Make sure you know the quality of your staff. I have seen one security staff member cause a bar room brawl reminiscent of a 1800s saloon throw down, and on the flip side I have seen one security member defuse a full-out gang fight. So when you hire security personnel, size is not all that matters; just because Mango can bench press a Volkswagen and is intimidating does not mean he is good at being a security staff member. Hire for quality, especially if you find the need to cut back on staffing. Quality always trumps quantity.

— Robert Casillas, President, Monsoon Group of Las Vegas