There is no mystery involved in measuring liquid fats or sticks of butter and margarine with measurements delineated on the wrapper. But for bulk fats, like shortening or tubs of butter, the displacement method works best. If you put these fats in dry measuring cups, pockets of air can form and throw off the measurement. Instead, if you want 1/2 cup shortening, fill a 1-cu liquid measure half full with water, then add the fat until the water reaches the 1-cup mark. Pour off the water.
Butter is 80 percent fat, so when substituting oil, which is 100 percent fat, use 80 percent of the butterΓÇÖs measure in oil; a robust olive oil should be kept to 75 percent. To substitute shortening for butter, replace it evenly, measuring by volume, as butterΓÇÖs water content equals the air in the shortening. However, if you are measuring by weight, use 15 to 20 percent less shortening than you would butter.
No matter the type of fat, each gram has 9 calories; each ounce has 250 calories. Measuring by volume is a less precise way to compare fats, because of the air, water, or other molecules they may contain. In general, per tablespoon, whipped butter has 70 calories, butter and soft or stick margarine have 108 calories; vegetable shortening has 111; lard has 117; and vegetable oils have 120 calories.
