A Reference Tool

Church growth ratios are a reference tool to aid in ministry action plans. Ratios are broad guidelines describing general characteristics that healthy, growing churches will exhibit.

The Bonsai Theory or 80% Rule

The 80% Rule observes that churches will grow to fill their available space. Ken Hemphill coined the term “Bonsai Theory” to illustrate this principle. A bonsai tree grows to fill the pot in which it is planted, but it will never grow larger than its container. Churches grow in much the same pattern in several areas:

• Worship Service Space
• Bible Study/Small Group Space
• Parking Spaces
• Nursery/Preschool Space

The 80% Rule says that a church will begin to plateau when it reaches 80% capacity in the spaces it has to grow. Win Arn applies the rule with an 87:100 ratio, meaning that the plateau begins at 87% capacity. Whatever ratio you use, filling available space has a chilling effect on your church’s growth potential:

• Worship Service Example – Church A has a 500-seat worship center, so it will actually reach capacity in that room when its attendance is 400. The church will begin to plateau at that mark and meaningful growth will cease unless additional space is found.
• Preschool Space Example – Church B has preschool space for 80 children. When the number of preschoolers exceeds that number, parents will perceive overcrowding and future growth will be dampened. Additional space must be created to facilitate continued growth.
• Parking Spaces Example – Church C has 150 parking spaces. When 120 of those spaces are filled with cars, the parking lot will be perceived as “full” and guests (who always arrive later than everyone else) will be frustrated trying to find a place to park.

• Leadership – 20% of the church leads the 80%.
• Tithing – 20% of church members give 80% of receipts.
• Small Groups – 20% of a church’s small groups produce 80% of its small group growth.
• Evangelism – 20% of church members account for 80% of the sharing.