Denier is a measure of the thickness of yarn used for weaving a fabric. When it is used in reference to hosiery, such as pantyhose and tights, denier lets the customer know the sheerness of the product.
The sheerness of a hosiery product is important because each type has a different look and strength.
An opaque (thick) hosiery, such as tights, would be worn with heavier fabrics and where the color of hosiery should be prominent in the outfit. Sheerer hose are worn for a lighter, more subtle look. Frequently, the more sheer hosiery, the less durable it is. Extremely sheer hose may not be the correct choice for daily wear.
Exact denier counts differ between hosiery makers, but generally fall within comparable ranges. For example, in the Calvin Klein hosiery line, the ‘ultra sheer’ pantyhose have a denier of 15, and the ‘soft opaque’ 40. The "matte sheer," intended for everyday wear, falls in between, with a denier of 20.
Manufacturers often list the denier on the package near other features such as sizing and amount of Lycra. Sometimes the product tag also shows the information.
Pantyhose sales have been on the decline since the mid-1990s; standards of dress have relaxed, especially in the workplace. This has allowed consumers who did not like the inconvenience and cost of pantyhose to move away from wearing them. However, manufacturers have had success with increased sales of tights and more non-traditional hosiery products.