The average size of an orange is approximately 2.5 inches in diameter, though measurements vary between species. Countries that produce oranges include the United States, Mexico and Pakistan.
Oranges between 5 and 6 ounces contain about 80 calories. They also contain 250 milligrams of potassium, according to the U.S. Food and Drug Administration. Contrary to popular belief, orange peels are not poisonous; however, they may be covered in chemicals if they are not organically grown. The vitamin C content in oranges can strengthen a person's immune system and protect cells from free radicals that could lead to cancer and disease.