3.5 feet would be the typical minimum for an adult. With 3 feet being a runt. 4 feet would be a normal, possibly above average slightyly, 4.5 is above average in size, 5 is a big boy or girl, 5.5 is massive, 6 feet is gigantic.

Then with weights, errr... I'd say anything over 2,000 grams is a big one.