If I'm making a pattern for a small keychain, do I need to include the amount of yarn?

I understand including the amount/yardage/weight of yarn used for bigger amigurumis and other projects. But this item is literally about 3 inches and 2 inches wide, and you can whip it up using scrap yarn. Also, I don't have any means to measure the amount used, so if it's necessary, I'd have to go buy a scale...