Quack quack! Is it a duck or a duckling? If you are buying it to cook, it is most likely the same thing. Domestic ducks available in markets are generally between eight and 16 weeks old and weigh between three and five pounds. You can also sometimes purchase just duck breast or duck legs. Duck can be roasted, braised or broiled, but also cooked "confit" style in fat. Duck has a very high fat content, and a general rule of thumb when figuring out how much to buy is to plan on about 1 1/2 pounds per person.