My packet of steel-cut oats says there are 391 calories in 100g and when I measured 2/3 of a cup it weighed 100g, meaning 1/2 cup weighs 66.7g. Therefore, according to my scales, 1/2 a cup (66.7g) equals (391 x 0.667) 260 calories.
WTF?!? how can my calculation be 105 cals over that from calorieking.com ???