The Whole weight vs measure and metric conversion thing

There is alot of confusion about weight and measuring recipes. I posted a reply under scratch baking but I think it bears repeating (you would think I like hearing myself huh :P)

OK some explanations first. Measuring a recipe by cups is a volume measurment or the space something occupies. Measuring by ounces and pounds is a weight measurment and has to do with the gravtitational pull of the earth...didnt think you were gonna get a science lesson did ya? Well baking IS chemistry...

So the weight of a cup of flour is NOT equal to the volume measurement. For instance one cup of flour is NOT equal to 8 ounces. A cup is only 8 ounces when measuring liquids. It takes up  the space of the cup measurement but the flour weighs less than water or milk. Liquid goes by volume. For some reason here in the US our home recipes use volume measurements. Someone somewhere figured out how many cups it took to make a cake and standardized the recipe.

 I wonder how many of you noticed that some days your scratch recipes dont turn out quite right and you have no idea why. Well for one thing each person measures a "cup" of flour differently. Some dip and sweep some spoon and some sift first and each method will result in a different weight. It can vary from about 3.5 ounces to almost 6! If you are using 2 or 3 cups of flour that can make a difference between a moist and a dry cake.

Now for the metric dilemma. Metric is a weight measurement if you are using grams and kilograms. Milliliters are a whole different critter which is a volume measurement like our liquid cup. Just so you know a liter is about 1.1 quarts or about 60 ml per 1//4 cup.

Now onto the weight conversion. Say your recipe calls for 300 gm of sugar.  An ounce by weight is 28.35 gms. So divide 28.35 into 300.  300/28.35= 10.58 ounces or .66 lbs about 2/3 lb.

Now if you were trying to convert your recipe using volume a cup of sugar will not be 8 oz. But let's say that you did figure that a cup of sugar is 8 ounces then if you tried to convert it to grams you would get 8 oz x 28.35 gm equals 226.8 gms. However the other day I measured a cup of sugar and it weighed 7.2 oz on my scale which is 7.2 x 28.35 gm = 204.12 gms

OK now let me show you the difference in weight vs volume. using the above example of 300 gms of sugar. 300 gms of sugar weighs 10.58 ounces. If you were to measure this amount using cups  then 10.58  oz is 1 cup plus 2 1/2  oz. (8oz plus 2.58 oz) Since the sugar I weighed was 7.2 oz by weight per cup, the sugar would weigh about 9 ounces if you measured in cups (1.25 cups X 7.2 ounces the sugar weighs per cup) 9 ounces is just over a half pound. (.56 lbs)

Yes your head is spinning but the simple math is 300 gms of sugar is 10.58 ounces not 9 ounces. Time to bite the bullet and invest in a scale. You will then be able to use any recipe whether it be cups, ounces or grams.