It looks like if you weigh them, 1.7 oz is approx. the same amount of calories (per calorie king):
Fruit, Fresh: Grapes, Red or Green (European type, such as Thompson seedless), raw 1.7 ounces = 34 calories
Fruit, Fresh: Grapes, American (slip skin), raw, edible portion 1.7 ounces = 32 calories
Hope that helps!