Liquid Measuring Cups

For years, the term "liquid measuring cup" meant one thing: a flared, graded cup with a handle, usually made from Pyrex-brand glass. No longer. Nowadays, the ubiquitous Pyrex shares retail shelf space with cups sporting a dizzying array of newfangled options, including gleaming metals, angled consoles, laboratory-style beaker shapes, and gradations broken down to number of teaspoons. Do these "innovations" go beyond bells and whistles? Is it finally time to upgrade from the classic Pyrex?

There's a clear distinction between liquid measuring cups and dry. A liquid measuring cup has multiple gradation lines. Dry measuring cups have none—there's a different cup for every amount. Dry ingredients and wet ingredients are also measured differently. The test kitchen measures the dry sort by dipping the cup into the ingredient, scooping a heaping cupful, then sweeping across the cup with a spatula (or the flat side of a knife) until the contents are level with the top of the cup—a method referred to as "dip and sweep."

We measure liquids by filling the cup until the surface of the liquid is even with the correct gradation line when viewed at eye level (which means stooping down to look). So far, so good—but be careful which part of the surface you're looking at. Liquids in a container have a tendency to form a meniscus, a slight curving of the surface. (The meniscus forms because water molecules are more attracted to the cup material than to one another, so they creep up the sides a bit.) When viewed from the side of the cup, the meniscus looks like a "cord" around the top of the liquid. To maximize accuracy, simply measure from the bottom of the cord, not the top.

The dry/liquid divide came to haunt a couple of the designs in our lineup. As we began our tests, it became obvious that metal is absolutely the wrong choice of material for liquid measuring cups: There's no way to view the gradation lines at eye level, much less spot the bottom of the meniscus.

As we watched panelists measure water with each model, another pattern emerged: They seemed to be filling the plastic cups at a faster pace. Additional research uncovered an interesting bit of physics: Water molecules are more attracted to glass than to plastic, so less surface curvature occurs with plastic cups—an enhanced clarity testers appreciated.

To minimize spillage, liquid measures should feature extra space between the uppermost gradation marking and the rim. Two of our models lacked this buffer zone, making liquid transfer a daunting task. The number of gradation lines was also important. Testers were annoyed by the sheer number of markings on some of the models, with column after column obsessively delineating useless equivalent measures in cups, third-cups, quarter-cups, milliliters, cubic centimeters, tablespoons, and more. So less may be more, but not if it's ridiculously less. One model had just three gradation lines (1/4 cup, 1/2 cup, 3/4 cup); nowhere except for the discarded packaging was there an indication that its full capacity was 1 cup. Other models, which performed well in every test, inexplicably had no 1/3-cup gradation markings.

Measuring, then transferring, cups of honey with each model convinced us of the virtues of roomy, rounded interiors. The skinnier designs had us reaching for our smallest spatulas, while the wider models made honey transfer quick work even with a standard-size spatula.