The pants size of a woman with a 26-inch waist is between sizes 4 and 6, or a size small. In order for a woman with a 26-inch waist to fit into a size 4-6, her hip size must measure between 35 and 36 inches.
The sizing of clothing varies between measurements of different parts of the body. The pants are measured by the waist, the hips and the inseam. A woman whose waist measures to fit a size small may need to purchase petite or long pants, depending on the length of the inseam. Clothing charts can be used to learn what different measurements mean for different clothing sizes.