In this online supplement to May's "Shake Your Money Maker" feature, find out tips for measuring the approximate cost of group exercise—and whether it’s worth the expense.

What is your group exercise class costing you?

1. Calculate the cost per class. First, take into account the total program cost. This should include the cost of equipment, instructor salaries, operation costs for the group exercise area, etc. For the sake of the calculation, let’s use a 15,000-square-foot facility as our model and assume that the program cost is $65,000 annually.

Now figure out the number of classes offered annually. If a club offers 28 classes per week, this works out to be 1,456 classes a year (28 classes a week multiplied by 52 weeks a year).

Next, divide the total program cost by the number of classes annually. In this example, you would divide $65,000 by 1,456. So each class costs $45 (rounded).

2. Calculate the number of members needed per class for a breakeven class:

A) Establish the average number of participations annually. Say, for instance, that 127 members take group exercise 2.5 times a week (on average). This comes to 16,510 participations per year (27 members multiplied by 2.5 times per week multiplied by 52 weeks).

B) Calculate the average income per participant per class. Here’s how.

First figure out the approximate income per club member. If, for instance, our 15,000-square-foot club grosses $675,000 annually with 1,500 members, then the approximate income per member is $450 ($675,000 divided by 1,500). Since we already established that 127 members take part in group exercise, multiple this number by member income. In other words, 127 times $450, which gives $57,150.

Next, add other fees that may be associated with group exercise (e.g., class charges). Let’s assume this number is $2,000. This means that the total aerobic income is $59,150 ($57,150 plus $2,000).

Take the total aerobic income and divide it by the number of participations. In this case, divide $59,150 by 16,510. This comes to $4 (rounded). That’s the average income per participant per class. C) Finally, divide the cost per class by income per participant, rounded up. So our 15,000-square-foot club would divide $45 by $4. This means that the club would need 12 members per class to break even.

Information courtesy of Michael Scott Scudder, owner/founder of Fitness Focus, a 10-year-old New Mexico-based consulting company. For more information, visit www.michaelscottscudder.com.