Here is a nice handy reference for serving sizes according to the USDA...

Fruit: 1 medium piece of fresh fruit, OR 1/2 cup of cut up fresh fruit, OR 1/2 cup of canned fruit in natural juices.

Veggies: 1 cup of fresh uncooked leafy variety, OR 1/2 cup cooked or canned vegetables.

Juices: 6 ounces (3/4 cup) of 100% fruit OR 100% vegetable juice (and contain NO added sugars)

Dried Fruit: 1/4 cup (e.g. raisins, apricots or prunes)

Avacado, coconut and olives do NOT count according to the 5 a day plan because of their extremely HIGH fat content!