I use them to shave my underarms and legs and down there also which is thicker hairs so this takes a toll on the razer I'd say two weeks at the utter most kind of expensive really

One cartridge thingy should be useful maybe three or four times depending on the thickness/coarseness of your body hair.

Well it does depend on how coarse your hair is...

Mine usually last 2-3 weeks.

deppends how often u use it nd how thick the hairs r