1, raw material cost: large underwear needs more raw materials to produce, such as fabrics or elastic materials, which leads to rising costs.

2. Design and manufacturing technology: extra design and manufacturing technology is needed for large-size underwear to ensure comfort and fit, which increases the production cost.

3. Supply and demand: Supply and demand affect underwear prices. The demand is lower, the supply is less, and the underwear of large size is more scarce because it is produced less, thus pushing up the price.