Measuring Your Ingredients: Volume versus Weight

It’s happened to many of us: You find an awesome keto recipe you want to try, you print it out, gather up all the ingredients, start looking at the instructions, and…. wait, what?! What the heck is this grams nonsense? What are they even asking for?

Ah, yes. You’ve entered the dreaded Metric Zone.

You see, cats and kittens, when we amateur cooks here in the United States try out a recipe, we expect to see familiar measurements, like cups, teaspoons, and tablespoons. So, it throws us for a bit of a loop to see a recipe with the ingredient amounts written out in grams or ounces (oz).

Why does this happen?

Well, to answer that question, we need to get a good glimpse into the world of the professional chef. In this world, food preparation is a science. This is a place where both accuracy and repetition are extremely important. When preparing a food, be it in a restaurant, a bakery, a creamery, or a candy shop, customers expect what ends up on their plates or in their mouths to be perfect. A dish should be consistently the same, and consistently delicious, regardless of whether you’ve stopped in on Tuesday or Saturday.

One tool chefs use to accomplish such a feat is to measure every ingredient in the most accurate way possible. That way, my friends, is almost always going to be by weight, and usually in grams since that’s the smallest weight measurement generally used in cooking, which means it’s going to be the most precise.

NOTE: The only exception to this rule is going to be for wet or liquid ingredients. Those are typically measured in volume, even in professional chefery (yes, I said chefery and I claim that new word as mine!), and there are special measuring cups designed to measure the volume of any liquid that is more than a tablespoon or two. You might also see liquid ingredients listed in fluid ounces (fl oz). This is not a measure of weight but a measure of volume, and you must not confuse the two. 8 fl oz of liquid does NOT weigh 8 oz on a scale. Mostly, Americans use cups as a unit of liquid measurement and non-Americans use fluid ounces (fl oz) or milliliters (ml).

Ok, I get all that. But how do you convert the weights to cups?

That’s where we tend to have a little bit of a problem. The short answer is, you don’t. Because you can’t.

“But why?” you ask.

Let me explain.

The reason why you can’t convert between the two is that they’re two entirely different measurements. They do not measure the same thing.

Say you go to the farmer’s market to buy pecans. You ask for a bushel of pecans, and the kind gentleman or gentlelady running the nut booth pulls out a container and fills it with your choice of nut. He or she bags it up, you pay for it, and you leave with a whole pile of delicious pecans. The actual weight of your pecans will vary every time you buy a bushel.

Now, let’s say the nut merchant doesn’t sell by the pint, bushel, or peck, but insists on selling by the ounce or pound. When you ask for pecans, the merchant is going to pull out a scale and weigh out the nuts. Depending on how large and dense the nuts are, you might have more or less in volume each time you buy them. This time their crop produced pretty average sized pecans and so your purchase of, say, a pound might fill up a quart sized ziploc bag. Next time, the nuts could be substantially smaller and the same bag might be overflowing. The time after that, it might only fill up two-thirds of the bag.

And that, my friends, is the difference between weight and volume.

Weight, very simply, is how much something weighs on a scale. Volume is a matter of being able to fill up a certain sized container. And the two are not even remotely the same thing.

Here are some handy visuals, for your consideration.

Lesson one:

This is a dry cup of finely ground almond flour. In the US, when we go to bake something, for example, we expect to be able to pick up one of these measuring cups and go to town with our ingredients. But here’s the problem: it’s not that accurate. Depending on how fine the grind is on the batch you have in your bag-o-almond flour, the weight of what fills this cup could change pretty drastically.

This is all the almond flour that was in that first picture, dumped into a glass measuring cup designed for liquids.

This is lesson two: cups designed for dry ingredients and wet ones are different. You can’t measure your dry ingredients in a cup made for measuring liquids. Now, for the weighing.

I measured that same cup of almond flour in both ounces and grams. As you can see, weighing this volume of almond flour in grams gave us kind of a weird measurement. But if I were a professional chef, and I made a cake, for example, using this amount of almond flour, I would need to use that same exact amount, every single time, if I expected to repeat the desired results in the future.

So, a cup is 85 grams, right? Can’t I just assume that and do the math from there?

Again, the short answer is no. But let me show you why.

This is a cup of xylitol. Again, note that the dry measurement isn’t the same when you put it in a liquid measuring cup.

Here is its weight:

Notice that even though this ingredient is dry and finely ground like our almond flour, it doesn’t weigh anything close. A cup of xylitol is significantly heavier than a cup of almond flour. So, if you assumed that the weight measurement for a cup of almond flour would be the same as a cup of xylitol, not only would you be wrong, your measurement for the sweetener in your recipe would be wildly off. This doesn’t just make a difference in taste and sweetness. In baking, ice cream making, and candy making, recipes rely on a specific chemical reaction happening in order to get the right rise, creaminess, or consistency. If your ingredients are off, sometimes by even just a smidge, the chemistry of your recipe is going to be off and you can get some pretty disastrous results.

But what about whole food ingredients?

Much as it would be insanely simple for everyone if we could just measure out a cup of broccoli and assume it’s going to be the same as a cup of nut, the truth is it’s not. I have several visual examples of commonly eaten keto foods to round out our lessons for the day.

Macadamia nuts and their weight:

Raspberries and their weight:

Pork rinds and their weight:

Apologies for the little bit of overkill, but I want to really drive home the point that when we tell you a weight measurement (on a scale) can’t be converted to a volume measurement (what fits in a container) we really aren’t just trying to give you a hard time. It’s also why you will very commonly find that I tend to give many dry ingredient measurements for my recipes in ounces and grams instead of cups (it also makes for a much more accurate carb count!).

My purpose here at My Ketogenic Kitchen is to help you succeed in the kitchen. Understanding how and why certain ingredients are measured in certain ways will go a long way to helping you successfully recreate your favorite culinary masterpieces, time and time again.