How we measure the thickness of a leather hide is a confusing and dated part of the leather industry. Leather is typically measured in ounces. You will see all over our site that we reference the ounce size of our leather for each product. The ounce is not a weight-based measurement; it correlates with thickness. If you look at this chart, you will see what I mean. Some people assume that the ounces must refer to the weight of a piece of leather, such as 1 square foot of leather. But that’s not the case. Leather can vary immensely in terms of actual weight/heaviness. It depends entirely on the type of leather used, how much dye is injected, how much oil the leather is holding, what type of animal hide, etc. So we’re not talking about heaviness here, we’re talking about linear thickness. In the chart, you can see what an ounce of leather equates to in the various units. The bars in the chart depicting the thickness aren’t exact so don’t hold you leather shoe up to your computer screen! A better physical point of reference would be a quarter (coin). A quarter is the equivalent of a 4oz. thickness, which is 1/16”.
Irons are an old school unit of measurement common in Europe. Years ago, during research and development, I used to hang out at an old school American leather boot factory. Some of the craftsmen were actually from Europe. And they always talked about irons. At first, admittedly, I had no idea what they were talking about. In the leather bag industry, we don’t use the term irons much. Everything is measured in ounces. There’s actually a special tool that looks like a cross between a tire pressure gauge and a tuning fork and you can pinch the leather hide to see how thick it is (in ounces). You can see one of these devices in this picture. It’s also worth noting that a leather hide itself can vary in thickness across the hide. Certain parts of the hide tend to be thicker than others. A special machine called a skiving machine or hand tools can be used to reduce the thickness of the leather. This is done from the suede side of the leather, not the outer surface.
As a great leather philosopher once said, “you gotta give me a bounce in the ounce.” In other words, leather thickness isn’t 100% precise. For example, an 8oz. piece of leather might range from 7 to 9 ounces across the piece.
So why does all the leather thickness stuff matter? Well, generally speaking, the thicker the piece of leather, the more durable and stiffer it will be. Of course, there are other factors involved too like the tannage (type of tanning method used). Most people know that you want to avoid leather that is too thin for durability reasons. But it’s also important not to use leather that it too thick because it won’t be workable and it may be too heavy or stiff to be practical in use. Finding that balance is where the art is. It’s what we strive to accomplish with each and every leather product we sell.