Hello Joan Thompson,
It sounds like your calculations are correct. You may need to charge more or have the clients pay per class attended. You could also charge a group rate of so many sessions in advance with a discount. The long term membership fee may not be the way to go. I like how you accommodate your clientele.
NAPS 2 B Fit
If people pay more for group-ex memberships than equipment memberships, you could add up the money for group-ex memberships to come up with your revenue piece. We used to have a $9.95 membership for just the gym and $19.95 for gym and classes. So we knew exactly what the group-ex was worth and who was buying it.
Then for your costs, you could allocate your rent and other indirect items based on square footage, and the director cost of instructor expenses, payroll taxes.