Someone recently asked me why all my recipes are in grams, so I thought I’d write a post about that. There’s two main points to discuss: volume versus weight and grams versus ounces.
Volume vs Weight
I have three arguments for weight over volume. I’ll start with the one relevant to the most people.
A cup of flour is a cup of flour, right? That’s certainly what I thought growing up, but once I really thought about it, the answer is no, it can’t be. There’s too much variation coming from the person measuring and possibly the cup used. I set up a small experiment to illustrate this. I took the three different 1-cup measuring cups I had handy and made nine attempts to measure a cup of flour - three with each cup.
I got a range of weights of 154-171 grams, which is a fair bit of variation. Even if we ignore that 171 gram reading (what did I do there?) the range is still 10 grams. This variation compounded over multiple cups of flour can turn into a big difference.
Another distressing fact is that these weights for a cup of flour aren’t even close to the 113 grams that King Arthur Flour suggests here. I measured out 113 grams of flour and it looks more like 3/4 of a cup. I checked the calibration of the scale against another one I have and it seems to be accurate. Other sites on the internet roughly agree with King Arthur Flour and these low-one-hundreds numbers seems to jibe with the rye flour I mill below, so I’m actually pretty confused here. EDIT 2/21/19 The weights on the KAF table assume that flour is sprinkled into the measuring cup, while I “scooped”, submerging the cup into the bag of flour. This packs the flour down, meaning more weight can fit into the same volume. Whoops!
I think my confusion makes my point though - could you imagine if there was this much variation in your plumbing or woodworking? Baking is an activity that requires precision, so volume for dry baking ingredients isn’t a good method of communication.
Baking is Ratios By Weight
Bakers write and understand recipes by looking at the ratios of ingredients by weight. Is this bread salty? How wet is this dough going to be? How much leavening power is there? All of this information and more is encoded in ratios, usually in the ratio of the weight of some ingredient to the weight of the flour. Theses are the percentages that I list in my recipes. I might do a more detailed post later, but if you want to read more now, the jargon is “baker’s math”.
Volume and the ratios bakers think about aren’t very compatible: a cup of flour and a cup of water are not equal parts by weight. There’s a lot of conversions involved in deciphering the secrets of a recipe written by volume, so if you’re interested in understanding recipes better then it’s best to think about weights.
Milling Doesn’t Preserve Volume
I mill much of my own flour. There’s lots of empty space in a cup of unmilled grain, so a cup of grain is not a cup of milled flour, but 100 grams of grain is 100 grams of milled flour. I milled some rye to illustrate this. There’s no reason I chose rye other than the fact that I needed some rye anyway.
The cup of rye berries I measured out weighed 200 grams. The milled rye has essentially the same weight, but I got about two cups of flour (this matches KAF’s weight chart I linked to earlier). I spilled some while figuring out the volume, otherwise I think I would have had 200 g exactly. A major benefit of milling your own flour is freshness, so I only ever want to mill what I need when I need it. I ensure this by measuring grain by weight.
Grams vs Ounces
Hopefully you are convinced of the advantages of weighing ingredients, but now you have two options: grams or ounces. My friends from outside the US would say that the metric system is superior and end the discussion. I mostly agree, but I wanted to do a little analysis to quantify this.
As I mentioned above, accuracy and precision are the keys to consistency so that’s where I focused my attention. The accuracy of your scale isn’t unit dependent; rather, it comes from purchasing and halfway decent scale and taking proper care of it. Precision is unit dependent, so let’s do a little analysis.
I have two types of digital scales in my kitchen. One has a maximum capacity of 5 kg or 11 lbs and measures to the nearest 1 gram or 0.1 ounce. I think this is a standard option and it’s the one I use most often. I also have a smaller scale which only has a capacity of 500 g or 1 lb but measures to the nearest 0.1 gram or 0.005 ounce. I use this to measure salt, yeast, and spices. Either way it may sound like you’ll be more precise measuring in ounces, but don’t be fooled by raw numbers in different units.
Let’s start with the 5 kg scale. One-tenth of an ounce is approximately 2.8350 grams, which means that this scale is 2.8350 times as precise on the gram setting than on the ounce setting. Things are a little better on the smaller scale. The weight 0.005 ounces is approximately 0.1417 grams. Since the scale is measuring to the nearest 0.1 grams, this means the grams setting is 1.417 times as precise.
Of course, neither measurement is wildly imprecise but given the choice, why not choose the finer measurement?
One Final Tip
The 5 kg scales (the ones accurate to 1 g) have a hard time with weights below 4 grams. The issue I usually encounter is that the scale reads 0 g until it suddenly jumps up to 5 or 6 g (or worse if you’re pouring quickly). The best solution is to invest in a scale accurate to 0.1 grams, but If you can’t or don’t want to, here’s a tip. A nickel weighs 5 grams (evidence below), so if you wanted to measure out 3 grams of something, place your bowl on the scale, tare the scale, place the nickel on the scale, then pour your ingredient until the scale reads 8. If you do happen to be using a recipe that uses ounces, you can use the same trick but with a quarter, which weighs 0.2 ounces.