I always knew there was different weights to denim, as so with all material, but I never really knew how it was measured. Today I found out how to determine the weight.
Fabric is measured in yards, so the weight refers to how much a yard of fabric weighs. So in simple terms, a yard of 10 ounce denim weighs 10 ounces, as does a yard of 14 ounce denim weight 14 ounces. One yard is equal to 914,4 centimetres and one ounce is 28,34 grams.
The heavier the denim, the less likely it is to bend, as with 20 oz denim for instance. Skirts, shirts and dresses are usually made out of 5 oz denim, because of the weight, it is lighter, softer and it drapes well. Denim jeans have traditionally been made from 12 to 14 oz denim, because it is a little heavier and more hard wearing.