Notes on Flour Weights and Measures

Just how much flour is in a cup of flour? That seems like a pretty dumb question, but actually, it isn't.

The short story of the rest of this page is: if you measure a cup of flour by scooping in the container or sack, and then tapping and leveling the cup with a knife, you will get a flour weight of about 5 ounces (142 grams). If you measure flour by sprinkling or spooning flour into a cup until it is full, and then leveling but not tapping, you will get an amount of flour that weighs about 4 ounces (113 grams). If a recipe doesn't say which type of volume measurement was used, you're probably best off using the spooning and leveling method. If you can, don't measure by volume at all! Instead, buy a scale and measure by weight to get the most consistent results for bread recipes. Below is a useful table connecting volume to weight for unbleached bread flour, using the spoon-and-level method.

The Details

The standard way to gauge how much there is of something, whether that something is an elephant, a grape, or the amount of wheat flour in a bread recipe, is by weight, not by volume. But, it isn't very convenient for a cook to have to measure something by weight, since a smart, possibly expensive tool is needed to do this (namely, a scale), as opposed to the cheap, easy-to-use measuring cup.

The problem is that measuring an ingredient by volume can result in a variety of different weights, i.e., different amounts of the ingredient, depending on how the measurement was made. In many recipes that use flour (cookies, for example), being off a little here or there doesn't really matter, but in yeast bread baking, it does. Too much flour in relation to water will often result in a "brick" rather than a nice soft loaf. Too much water compared to the amount of flour often results in another brick: the gluten structure isn't strong enough to support the loaf after it rises, and it collapses when the baking begins.

Luckily, many items in recipes are easily quantified, for example, "one medium tomato" is reasonably unambiguous. Liquid items are also no problem: a cup of water is 8 ounces by weight, and it is easy to tell when the cup is full ("fill to the line"). You can't really get a different amount of water in that cup (assuming you've filled it correctly to the line of course :), since it is very hard to compress water, whether in scientific laboratories or in the homes of physicists who like to use bread machines.

But flour is another matter. It is easy to get different weights of flour in a given measuring cup. My bread machine recipes (which, like most cookbooks, show flour measurements by volume) assume that the cook is scooping the flour out with the cup, then tapping and leveling the cup. Both the scooping and tapping tend to push out any air pockets in the cup and more densely pack the flour. Another very popular way to measure flour by volume is to sprinkle or spoon the flour into the cup, and then level the cup without tapping. This results in less flour in the cup: there will be small air pockets. The scoop-and-tap method usually results in about 5 ounces of flour in the cup. The spoon-and-level method usually results in about 4 ounces of flour.

To complicated things further, different measuring cups often lead to different weights of flour per cup. Some cups, which seem to be designed for flour (flat rims on top, separate cups for 1/4 C, 1/2 C, etc.), are actually full slightly below the rim, i.e., they are designed for liquids. These cups will yield more flour per cup when filled to the rim than true fill-to-the-rim cups. I was easily able to get about a 1/2 ounce difference in flour weight per cup using two different measuring cups. And, finally, note that rye flour typically weighs about 1/2 ounce less per cup, and whole wheat flour weighs about 1/4 ounce more per cup than bread flour.

All is not lost, however. Most good bread recipe books will suggest how to measure the flour for best results. If yours doesn't, or you have a standalone recipe, then you are probably safe to assume the spoon-and-level method. Some well-known cookbooks (e.g., The Joy of Cooking) suggest that this method should be standard, and if you need to measure sifted flour by volume, it is the most convenient. However, I've seen several good cooks using some combination of the two methods, e.g., scooping but not tapping, and of course they write their recipes assuming their own particular methods.

Now you can understand why the question of how much flour is in a cup is really kind of complicated. If you can afford a decent (electronic) kitchen scale, the best way to go is not to use volume measurements for flour ingredients in recipes; instead, measure by the weight of the flour. To convert your time-tested recipe(s), measure the flour the way you normally do with your cup, weigh it with the scale, then simply write down the flour weight in your recipe. Next time, just weigh the flour to get to the right amount. No mess, no leveling, no cups, no fuss.

The table below gives the weight of King Arthur bread flour corresponding to the volume measurements in my bread machine recipes, which assume the scoop-and-tap method, or about 5 ounces of flour per cup. This table is useful mainly if you want to use my recipes but measure by weight.