Americans are not a systematic people, at least not when it comes to measuring out cooking ingredients. Pick up just about any cookbook and you will find a hodgepodge of units—pinches, teaspoons, cups, ounces. Take, just for example, the recipe for butternut squash gnocchi in The One-Block Feast, an appealing new book by the staff of Sunset Magazine. It calls for, among other things, 3 pounds of butternut squash, 1½ tablespoons of honey, ¾ teaspoons of sea salt, 9-10 ounces of chard, and a single large egg, as well as both dry ingredients (the flour), and moist ingredients (ricotta) measured in cups. Someone following the recipe would presumably scoop the salt or honey into standardized measuring spoons, use graduated liquid cup measures for larger volumes, and possibly weigh the produce.
Such variation and, particularly, the reliance on volume measurement, drives technically minded cooks absolutely bonkers. Scooping teaspoons of dry ingredients and eyeballing liquid cups, they argue, is imprecise, and messy to boot. One of the most active protesters, food writer Michael Ruhlman, wrote of his frustration in following a roll recipe which called "maddeningly" for 5 cups of flour: "I found myself scooping out cups, scraping off the top, flour drifting over the counter and cutting board. But more than the mess, was the variable amount: given that flour can weigh 4 ounces a cup or as much as 6 ounces, I didn't know if I had 20 ounces of flour or 30 ounces—a 50% difference." Ruhlman ended up with strangely stiff dough. To avoid such confusion, Ruhlman urges cooks to weigh ingredients with kitchen scales.
Ruhlman is not alone: When Nathan Myhrvold and his crew put together their magnum opus Modernist Cuisine, they made a point of measuring everything in metric weight (even water). "If you use a fraction of a percent more or less of certain gelling agents or thickeners—for example, one extra gram of the compound per liter of liquid—that imprecision will ruin the recipe," Myrhvold writes in an introduction to the book's methodology. Likewise, Ferran Adria, the iconoclastic Catalan chef and one of Myrhvold's inspirations, cites the 1999 adoption of precision scales in his kitchens as a major creative breakthrough. The scales allowed him to calibrate the quiver in his otherworldly gels, and eventually other surreal textures as well.
But you don't need to be an iconoclast to appreciate a scale in the kitchen. Digital scales today are small—they fit into kitchen drawers—cheap, and straightforward to use. A perfectly good digital scale runs about $30 (roughly the price of a set of dry measuring cups plus a liquid cup measure). With it, you can measure directly into a mixing bowl, pushing a tare button to subtract the weight of the container. And if you're working with a recipe that's written with metric measurements, your computerized scale will switch the units for you.
Weight measurements also make scaling up or down particularly easy. Once everything is measured in either ounces, or even better, grams, there are no more fractions to screw up, as with cupfuls of flour; no tricky conversions from fluid ounces or tablespoons to cups. [Pop quiz: Do you know a) how many teaspoons are in a tablespoon? b) Tablespoons in a cup? C) Fluid ounces in a cup? See answers below.] Typically, professional recipes are written up as formulas pinned to an anchor ingredient. So a bread recipe that is anchored upon flour (which is assigned 100 percent) might then call for 1.7 percent yeast and 80 percent water. To change the recipe, a cook can simply weigh out the amount of flour she wants to work with and then multiply that amount by .017 for the yeast, and 0.8 for the water.
Volume measurements used to be state of the art: When Fanny Farmer and her immediate predecessors rejected vague quantities like "a handful" and pushed American cooks toward standardized measuring cups, it seemed like significant progress toward consistency in the kitchen. Why did they stop short of scales? As historian Laura Shapiro points out in her book Perfection Salad: "the European practice of weighing ingredients on a kitchen scale, precise though it was, seemed slow and cumbersome to impatient American cooks."
Today, however, scales are so simple it seems odd that cooking magazines and book publishers haven't embraced a shift. The real problem is that Americans are pretty stubborn—otherwise, we'd be in sync with the rest of the known world on the metric system. And admittedly, changing a system of measurement isn't easy—it's a bit like switching languages. (I can eyeball a cup of flour, for example, but I'm not so good at guesstimating ounces of it.)