Good Question, in Canada and US a weight is not given in the conformation standard. The Havanese does not have to be really light. Depending on the size of a Havanese the weight ranges from 7-22lbs. I own a very athletic agility Havanese that stands 11″ at the withers. She weighs 18-20lbs depending on how much training she does and her muscle mass.
From the AKC Standard
“The height range is from 8½ to 11½ inches, with the ideal being between 9 and 10½ inches, measured at the withers, and is slightly less than the length from point of shoulder to point of buttocks, creating a rectangular outline rather than a square one. The Havanese is a sturdy little dog, and should never appear fragile. A coarse dog with excessive bone is likewise contrary to type and therefore equally undesirable.”
check out this site for the abc’s on Havanese…