I have had a full carryon that was 17-20 pounds. Mostly clothing for warm destinations, no laptop or other heavy items. The bag itself is a non-wheel backpack.

Note that 7kg (about 15 pounds) limits are common on Asia-based airlines. Enforcement may not be all that strict, though. (The above bag was only weighed once out of four possible times by airline agents, who let me carry it on anyway despite it being slightly over the weight limit.)