the simple formula for calculate gym equipment quantity as follow:
QTY = Area / 8
for example, you have a place 400 sqm, keep 100 sqm as changing / locker room, you have 300 sqm for machine, 300/8=37.5, means 37 PCS is enough for your gym, it will not waste room, meanwhile not crowded.
but if the quantity of your cardio exercise equipment more than 50% , you can use 7 to replace 8 in above formula. remember do not less than 7, or you will have no room to walk.
Find a good architect to design
the premise is that you get accurate dimensions of all machine or original 3D image which is not a simple job, the fact is most suppliers from China have no ability to meet this requirement, the right screen shot shows what happened to one of our customers and his friend who is also a gym owner