Denier is a unit of linear mass density of fibers. This means two things. Firstly, the higher denier is the more opaque a fabric is. Secondly the higher denier is the thicker is the material.
Denier is commonly used by hosiery manufacturers to determine thickness and transparency of their products. So for example if you want to buy 8 denier tights it means that the tights will be barely visible on your leg and made of a very thin material. 8 denier tights would be also more ladder prone than for example 40 denier tights.
Deniers have been simplified and gathered into six groups. So we have products in the following sets:
- Less than 10 denier – ultra sheer
- 10-20 denier – sheer
- 21-40 denier – semi opaque
- 41-69 denier – opaque
- 70-99 denier – thick opaque
- 100 denier and more – mega thick opaque
So for instance if you spot a semi opaque tights in a shop it means that the tights are of thickness between 21 and 40 denier.
Please mind that although 40 denier products look like opaque they are still see through. For example there are often 40 denier leggings on sale. You can’t see the colour of your skin through them, but if you wear white underwear, then you panties will be barely but still visible. 40 denier leggings shouldn’t be worn without a skirt or long shirt. Safe barrier is 50-60 denier.
So we know that the higher denier the thicker and more opaque material is. But with thicker material comes to action thermal efficiency. This means that the colder weather the higher denier we should wear and the hotter weather the lower denier. 300 denier tights or leggings are often called winter warmers due to their thickness.
Please have a look at the picture below. It shows how the denier covers your skin. 0 denier means that there is no fabric covering your leg. On the right there are horizontal lines of different thickness, they show the growing thickness of the material with the higher number of denier (it does not reflect the real thickness of the material).