It’s notoriously difficult to accurately measure how big a church is.

Official membership may be defined differently from one church to the next, thus not allowing accurate comparisons; criteria for what constitutes a member or standards for membership may vary widely not just from church to church, but over time within the same church; and membership can be affected by outside factors such as denominational dues being pegged to membership (which tends to lower the number of members counted). I believe official membership has an unacceptably high margin of error, perhaps as high as 50%, and so I tend to discount it as a useable metric.

Other measurements have been devised, and the most common in mainline and liberal Protestant congregations is “active membership.” Active membership is determined by counting the total number of people present in the building during weekend worship services each week, and taking the yearly average. Margin of error is usually under 10%, as long as records are taken every week. However, active membership does not count other people who might be active in the congregation, e.g., people who are active with the Women’s Alliance but who do not come to worship services regularly.

Given the often gross inaccuracies of these two methods of determining congregation size, my feeling is that we need additional metrics. Since congregational size is such a slippery concept, I suspect it is best determined by using several different metrics together.

One obvious additional metric might be to determine the number of volunteer hours people contribute to the congregation. This would take into account all the people who seem to feel that the church’s mission and goals are important enough that they are willing to devote their precious volunteer hours to the church — and it would include those who may not come to the worship service. It will be difficult to accurately measure volunteer hours, and the best we could hope for is an approximate measurement. However, it should be possible to come up with some basic techniques to make a reasonable estimate of volunteer hours, e.g., determining the number of people who volunteered in any capacity during the year, and estimating the average number of hours per volunteer. Even counting the number of volunteers alone would provide useful information.

Another obvious metric for determining church size is obvious:– determine the size and sources of operating budget. The size of the operating budget should tell us the potential impact the church could have on its members and on the wider community. We would also need to know the sources of the operating budget, broken down into member contributions, endowment income, rental income, and grants — a smaller percentage of operating budget coming from member income would most likely indicate low member commitment and/or fewer members.

One or two additional metrics would be very useful for those of us who want to take organizational development and growth seriously. It’s too easy to say, “Oh, there’s just such a good feeling around this church so we must be growing.” Good feelings are important, but in my experience there is not a strong correlation between good feelings and growth — good feelings may (or may not) be a necessary precondition for growth, but in most cases good feelings do not lead to or cause growth.