5 Helpful Church Growth Ratios

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.

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:

  • 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

7:10 Worship/Small Groups Ratio

Small groups 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.

  • Church Example – Church A has 500 in morning worship attendance and so it will likely average around 350 in Sunday morning small groups.
  • Non-Traditional Churches – Innovative churches have home-based small group ministries that meet throughout the week, so the ratio will be dfferent for these churches.

Paid Staff Ratio

A church will normally have 1 full-time minister for every 100-150 people who attend morning worship services. Part-time ministers can fill in the growth gaps. Some churches will use 2 part-time staff members in place of 1 full-time minister as they compute the staff ratio.

  • Church Example – Church A has 375 people in its morning worship service, and so it will likely have betwen 2½-4 full-time staff members (achieved with a combination of part-time and full-time ministers).

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.

  • Single Service Example – Church A owns a parcel that includes 8 acres of land, so its potential growth ceiling on that property is around 800 people.
  • Multiple Services Example – Church B owns a parcel of 5 acres, but it has chosen to conduct multiple services at different times. This allows the church to exceed its natural growth ceiling of 500 people, as long as people don’t occupy the same space at the same time (which is why dual worship services and small groups often don’t solve space problems).

Many churches multiply the growth potential of their land and buildings with creative solutions to the limitations they face. Some have multiple services on Sunday morning or create a schedule with services at different times or on different days. 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.