TL;DR: Volume units such as cups may not be consistent across various recipes. Volume is challenging to measure, for liquids due to surface tension (menisci) and density changes concerning temperature, and for solids because of varying granularity. Additionally, it is challenging to obtain the exact measured value for both. Therefore, use mass units when measuring ingredients while cooking. If you don’t have a scale, then buy one – it’s not expensive and will change the way you cook forever.
Since I was a young boy, I always wanted to get into cooking. Being able to make lots of delicious things for yourself, very often for a much lower cost than in shops or restaurants (up to even 4 times (!) as cheaper) seemed like a dream. But when I first started, making even some basic recipes would sometimes just fail, no matter how much attention and care I would put into them. And I just didn’t know why that was – I did all the things the recipe called for. I did things step by step and still the result would be, to put it lightly, a disappointment. Sometimes I would even think that people sharing those recipes didn’t know anything about the dish and were trying to lie to me that the recipe would make something decent.
I found out that those recipes had flaws in them. I would never achieve the result that was accompanied with the recipe if I did not change the amounts of ingredients that the recipe called for. I was puzzled – how come can a recipe give such different results? Sometimes even when done twice, the created dish was different from the first time. Even when I thought I did everything the same way. Is my memory faulty? – I would sometimes think.
Then it struck me. The recipes I used very often used cups for telling how much ingredient I needed. Aha! – I thought. I’ve got you now! I need to look up what exactly a cup is. At home, I had different cups. Some were smaller, some were bigger. One of them even had a volume of 0.75 litres!
So, I did some research. I knew that some people would use the cup that they had available, but others were using measuring cups. Yes! If I buy a measuring cup, my problems will finally go away. So, I went to the shop to find some measuring cups that I could use. And I found some. I could even choose from different types, how great! Well… as I looked closely, they were not only different in design, but also had other capacities. The smallest of the available ones was just over 200 ml, and the biggest was about 250 ml. That’s almost 50 ml difference. Too big if used in cooking. I went back home to do some more research and found that the most popular size is close to 250 ml. So, I bought the 250 ml ones. And I also found some measuring spoons, so I bought a set of those too. I was pleased, because perhaps now I could increase the variety of results.
I did some more cooking. I even found recipes that called for those specific measuring cups. It was better, but still I wasn’t fully satisfied. Especially when it came to baking. That still was often a disaster.
Around that time, I also bought a scale that I had never previously used in the kitchen. As I found out later, when the recipe called only for weighing ingredients, the results were almost always spot on. So much so that I was even discouraged when the recipe used any volume metrics for the ingredients as I knew that it would be harder to recreate the author’s intentions.
I did some testing. I would grab common ingredients like flour, sugar, two types of salt, water and milk, and try to measure some volume units of it. Later on, I measured the weight of what I had. So, I did that and for consistency I repeated the same thing a couple of times. To my big surprise the difference between some repetitions was as high as 20%! And no matter if I measured dry or wet ingredients, the differences could be that big! No wonder was it was hard to recreate the recipes. It’s just too hard to measure the exact value when dealing with volume. Liquids have menisci that you may overlook and dry ingredients may have different granularity.
The biggest difference was in salt. I had two types available, one was table salt, whose crystals were very fine and the second one was sea salt, whose crystals were quite coarse. And when I took a spoon of each of them and then I weighed them, I found out that in a spoon there is twice as much of table salt in grams than in sea salt! That is a difference that would make a dish oversalted or bland if the type of salt was incorrect! Wow!
Today, I almost never measure ingredients by volume. If I create a dish and want to remember what I added I always weigh them, and that’s what I note. When I share a recipe, I always provide the quantities in mass units. That way I can ensure that if somebody has the same ingredients as I did, they should get close to my results.