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:
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:
Ken Hemphill, The Bonsai Theory of Church Growth: Grow Your Church to Its Natural God-Given Size (Nashville: Broadman & Holman Publishers, 1991).
The Pareto Principle or the 80:20 Rule
Any organization manifests a directly proportionate 80-20 relationship in leadership, commitment and productivity. Consider some examples of this principle applied to church life:
7:10 Worship/Small Groups Ratio
Small group attendance tends to lag morning worship service attendance by a 7 to 10 ratio. Most churches will have a Sunday morning small groups attendance that is 70% of the total morning worship service attendance. This ratio may vary slightly in different regions of the country and among different church types.
Paid Staff Ratio
A church will normally have one full-time minister for every 100-150 people who attend morning worship services. Part-time ministers can fill in the growth gaps. Some churches use two part-time staff members in place of one full-time minister as they compute the staff ratio.
Win Arn, The Church Growth Ratio Book: How to Have a Revitalized, Healthy, Growing, Loving Church (Monrovia, CA: Church Growth, Inc., 1990).
1:100 Land Use Ratio
In most situations, each acre of land will support approximately 100 people in morning worship services and small groups. This ratio includes allowances for worship, groups, parking, green space and road access. Note that this ratio may vary in your situation based on available external parking, local building codes, worship service times and other factors.
Many churches multiply the growth potential of their land and buildings with creative solutions to the limitations they face. Multiple services on Sunday morning or a schedule with services at different times or on different days is the obvious solution. Other churches opt to have satellite churches in multiple locations. Still others send out people to plant new churches when the growth potential at their current location has been reached.
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