That's part of why it's worth $20. There would need to be some brand research done, checking the fitting and sizing of various brands, so you could know that "

That's part of why it's worth $20. There would need to be some brand research done, checking the fitting and sizing of various brands, so you could know that "with a 31 inch waist, measured around the navel, I would fit in 30 inch Gap jeans and 32 inch Wranglers." That trip to try on those two pairs of jeans cost you what, an hour? two hours?