Men's and women's clothing are almost always sized differently. While some pieces use logical measurements with inches, others declare only vague size numbers at random. Often, however, men's and women's clothing are quite interchangeable for many reasons, and a person of the opposite sex may find herself at a loss when trying to determine what size would best fit her. When looking at clothing for men or women, it is useful to know how the two sizing standards differ.
Add two to a men's shoe size or subtract two from a women's shoe size to determine your size in the opposite. Men's shoe's generally run larger by size than women's, so if you wear an eight in women's you will likely fit a six in men's.
Subtract 21 from the inches of men's trousers or add 21 to the size of women's trousers to determine your size. Men's waists are measured in inches, while women's are measured in size. If you wear a five in women's, grab a 26 inch waist for trousers. The second measurement, the inseam, will remain the same for you.
Notice the inches in men's and women's shirts. Shirts can be trickier to measure because of the different measurements. The inch measurements are often the same, though a woman might want to grab a shirt a size of two smaller because of the large neckline in men's shirts and the larger sleeves around the biceps. Men should grab a shirt up to two three sizes larger because of the small necks and shoulders.