Hula Hoop Sizing: Inner Diameter vs Outer Diameter

By shelledhoops, Jul 30 2015 12:07AM

ID vs OD Diagram

Whether you are a first time buyer or have several hoops already, the language of hoop sizes can get confusing. More specifically the concept of inner versus outer diameters can rattle your brain a bit when trying to choose the right size, or making sure you ordered the size you intended to. These terms are used in describing the tubing itself, so how thick it is, and of course the diameter of the actual hoop.

When it comes to the tubing itself, the HDPE and polypro tubing used for LED hoops (or the colored tubing used for day hoops) is categorize by the tubes outer diameter. So the 3/4” tubing measures three quarters of an inch across from each outside rim…. the measurement takes into account the wall thickness of the tube. The inner diameter of that same tubing measures 5/8” which is why the 5/8” od tubing is used as the insert tubing for connecting 3/4” hoops.

So that may be pretty straightforward, but what can be confusing is when you are used to the day hoops made from the black PE tubing at hardware stores. This tubing is categorized by inner diameter, so the 3/4” id tubing at the hardware store is actually quite different in size and weight from the 3/4” od tubing that say your first LED hoop might come in. If you are used to that 3/4” black PE tubing and would like to order an LED hoop that compares nicely to that tubing than it is actually the 7/8” HDPE tubing that you should order. Some people also get confused by this because they know that they like the thinnest day hoop tubing from the hardware store, which is the 1/2” id tubing, so they think that they should order the thinnest LED hoop tubing we offer, which is the 5/8” tubing. Again, these two do not compare well…the 1/2″ id black PE tubing actually compares nicely to the 3/4″ od HDPE tubing. The 5/8” tubing is thinner and lighter. So if you are going to order your LED hoop with intentions of it being similar to your favorite daytime taped PE hoop than this should help you know which tubing is most appropriate for you to choose.

More commonly the inner and outer diameter terminology is used to describe the size of the hoop itself. Inner diameter (id) is measured from one inside edge of the hoop straight across to the other inside edge. Therefore, the inner diameter measurement does not take into account the thickness of the tubing. Outer diameter (od) is measured from one outside edge of the hoop across to the other outside edge, therefore taking account of tubing thickness in the measurement. The thicker the tubing, the more different the inner diameter is from the outer diameter. So with 3/4″ tubing, for example a 35” id hoop would have a 36.5” od measurement. And for a 32” id hoop, the od would be 33.5”. So the difference between inner and outer diameter for the 3/4″ tubing is 1.5” (since ¾” + ¾” = 6/4 = 1.5). Basically whatever the tubing thickness is, if you double it then that is what the difference between the id and od of the hoop would be. Going off of this then, for the 5/8” tubing the difference between the inner diameter and outer diameter of a hoop is 1.25”. Therefore a 28” id hoop has an od of 29.25”. Or a 28” od hoop has an id of 26.75”. We are always happy to do conversions in either direction for customers, but it is nice knowing how these measurements and conversions work.

So what’s more commonly used, the inner diameter or outer diameter? In our experience inner diameter has always been more popular but we really have been seeing a lot of each lately when given size preferences for hoops. I think the reasoning behind inner diameter being more common is that the inner diameter of the hoop is the part that actually comes in contact with the body while hooping. More often than not we are still given inner diameters on orders, but the outer diameter specs have been getting more popular…especially on the small 5/8” hoop orders it seems. Perhaps the rise of so much off body style hooping has shifted the way people measure their hoops! Or maybe not, but it’s logical thought!

I hope you found this explanation of inner and outer diameters useful for better understanding how hula hoops and the tubing used to make them is measured! If you are still confused please feel free to contact me. Otherwise go ahead and start shopping for some new hoops!