Denim weights anywhere between 8 ounces and even up to 20 ounces.
20 ounces is quite rare, it’s an extremely heavy denim, the jeans almost stand up by themselves. The average raw men’s jeans are about 12 oz.
Just to get an idea check out the Naked and Famous website.
The heaviest pair of jeans I personally own are the Raleigh 14 ounce men’s. They are drop-dead the best and sturdiest selvedge jeans I have ever worn and it is taking me for-ev-er to break them in. Yeah, also because I am so fickle and don’t wear those as much as I should… AND because it is way way toooooo hot to even think about those right now LOL