I’ve led the discipleship/groups ministries at three churches (so far!). As God allowed me to serve these churches, I discovered there are unseen forces at work in Bible study groups. If you are a group leader, there are at least 5 key numbers affecting your Bible study group. Did you know?

The number 1. Is your group attendance plateaued? Are you in decline? The number 1 may be part of your challenge. The number 1 represents a key aspect of group life: your group needs 1 prospect for every active group member. If your group has 12 active members, you need a list of at least 12 people who are potential new members for your group. A relationship must be cultivated with these adults, which means that every time your group does something fun, the people on your prospect list should be invited to spend time with your group. As your group serves together beyond the church campus, invite your prospects to join you. Group members should regularly invite their friends, family, and neighbors to your group’s Bible study time. Groups don’t grow because they don’t have a group of people they are cultivating for membership in the group. Here’s a simple exercise to help your group discover prospects: ask each group member to write down the name of 5 people they know who do not attend church, but are the right age to attend your group. If you have a group of 12 people, you would discover 60 new prospects in no more than 5 minutes!

The number 18. Most ongoing groups tend to turn inward when they’ve been together more than 18 months – that’s what the number 18 reminds us. Former Lifeway Director of Sunday School, David Francis, was known for saying, “The natural inertia of any group is to turn inward.” He’s right. I’ve seen it in the Bible study groups I’ve led. If your Bible study group has been together more than a year-and-a-half, ask yourself how many guests your group continues to see. Not as many as at the start? That’s fairly typical, and that means group leaders must remain especially vigilant in keeping the group focused outwardly, welcoming guests warmly and assimilating them into the life of the group.

The number 15. This number represents the square feet per person that is needed in adult groups. People need personal space, and the place they meet needs enough spread-out room to make them comfortable. If your group is in a cramped space, people will stop attending, and possibly choose another group that has more room. Let’s say the place your group meets has 300 square feet of space. Divide 300 by 15 sq. ft. per person, and you’ll see that the room could hold a max of 20 people. But keep reading, because that’s when the number 80 comes into play!

The number 80. When a meeting space is at 80% of its capacity, it’s full. There may be some empty seats, but visually the room looks like it is full, and that discourages people from continuing to attend. If people cannot sit where they want, and others are forced to sit on the front row, they’ll think twice before coming back. How do you know if your meeting space is at 80% capacity? Do the exercise above and determine the maximum number of people the room should hold, and multiply that by 80%. A room with a capacity of 20 people will tend to max out attendance when 16 people regularly attend the group’s Bible study. Can a group push past 80% capacity? The answer is yes…in the short-term. When groups run close to 100% capacity, they almost always drop below the 80% threshold as time passes. The solution? Start a new group!

The number 12. The number 12 is the optimal size for a Bible study group. You may be part of a much larger group, but those are not ideal for making disciples. Yes, you can teach the Bible to a larger group, but discipleship requires proximity. Jesus poured his life into 12 men, and even went a step further with his inner circle of three (Peter, James, and John). In the book Countdown by David Francis and Rick Howerton, one a Sunday School expert and the other a small-group expert, agreed that 12 people per group was the ideal size (not just them, but other experts were surveyed, too). There was a caveat, though. They said that the ideal size was 12, plus or minus 4. A group is optimally positioned to make disciples when it has a minimum of 8 people, and a max of 16.

Pay attention to these key numbers, because they are in play at all times! If your group is too large, start another one. If your group doesn’t have enough space, don’t ask to move to a larger room – start another group! If you don’t have a prospect list you’re constantly working, then identify potential group members and go after them!