Sheets are hardly a new or complicated product. So we think companies should be able to make sheets that are strong, fit well, retain their shape, and don't cost hundreds of dollars per set. Until that happens, follow these tips from our experts.

Learn the Lingo

Along with thread-count, you may see terms like long-fiber, pima, Supima, and Egyptian cotton. (If you see Supima, that’s a brand trademarked by the Supima Association of America that simply means pima cotton grown in America.) Typically, long-fiber cottons are stronger and less likely to pill.

Terms like percale, sateen, and twill are used to indicate how the fabric is woven. Percale is closely woven and feels crisper, while sateen has a softer feel and a glossier look. Twill weaves create a heavier fabric that can feel soft or crisp.

You may also see the term "cotton rich" to indicate that the sheet is made from over 50 percent cotton with the rest from other fibers. In some cases the word cotton will be in large type with rich in much smaller print, so you might miss the distinction.

Despite the claimed benefits of all these attributes, as with thread-count, our testing doesn't show any correlation between these attributes and sheet performance.

Speaking of claims, you should be dubious of environmental claims. The Federal Trade Commission has ordered retailers to stop labeling and advertising rayon textiles as eco-friendly bamboo. Once the plant fiber has been processed, it's rayon, not bamboo. (You may also see this labeled as bamboo viscose, but it's the same fiber.) In addition, the processing uses toxic chemicals that emit hazardous air pollutants during manufacturing.

Softness

Feeling new sheets in the store will help you figure out how the sheets will feel once they're washed. Our testers found that even after a year's worth of washes, most sheets felt close to their initial softness. To help you choose, our trained sensory panelists judge the sheets' softness and crispness after five washings.

Size Matters

Measure your mattress' height, including mattress pads. Remember that padding settles, so measure in at least two spots away from the corners. While you should buy sheets that have a deeper pocket than the thickness of your mattress, it doesn’t always mean that they'll continue to fit after you wash them numerous times.

In our tests, we wash fitted sheets according to the manufacturer's directions up to 25 times—the equivalent of about a year's worth of washing if you change your sheets every two weeks. After every five wash/dry cycles, we restretch the sheet over the mattress to see whether it fits. We saw shrinkage of up to 6 percent in all the cotton sheets we tested. In almost half of the samples, there was so much shrinkage that the sheet no longer fit the mattress. Only one cotton sheet we tested lived up to the claim of "deep pocket sheets;" few fit mattresses that were 18 inches tall.

Keep Your Receipt

You should wash your sheets before sleeping on them to remove finishes or excess dye. If the fitted sheet shrinks so much that it’s difficult to put on your mattress, or if you don't like how the sheets feel once they're washed, plan to return them. You’ll need your receipt to do that and also to take them back if the sheets are mislabeled or a piece of the set is missing.