The 80% rule states that when a building has reached 80% of capacity it is full. This is because we all have a sense of personal space. Do an experiment: the next time you find yourself in a conversation, note how far away from the other person you are standing and then take a step toward them. When I once did this to a friend he started to stutter and turn red. In the post-experiment debriefing I found out that his first thought was to punch me. I am not suggesting that your visitors will become violent when your facilities are too full, but we all need a certain amount of space to make us feel comfortable. This is the phenomenon that dictates the 80% rule. The compliment of this rule is that the remaining 20% of seats will be in undesirable locations--such as the front row.
One way to overcome this problem is to constantly monitor your church attendance. When you realize you are averaging about 80% capacity, know that you’ve overgrown your current location. In fact I’ve heard some people aim for 75% capacity to give them enough time to plan options for accommodating more people. Solutions to this problem depend on the nature of your facility. If you own your own building, it’s time to start a new service. If you are renting, you need to find a larger location (or you could start another service as well).---you can read the entire post here