Calories in zucchini. In uncooked zucchini (also known as courgette) including the skin, there are: 19 calories in one small size zucchini (4.2 oz or 119g) 31 calories in one medium size zucchini (6.9 oz or 196g) 52 calories in one large size zucchini (11.4 oz or 323g) 4 to 5 calories in each ounce or 28g of zucchini.