Adequate thickness for your preferred style of yoga. Most yoga mats have thicknesses around 1/5 inch -- which is recommended if you're practicing on a hard surface -- but premium mats closer to 1/4 inch and super-thin yoga mats and towels around 1/20 inch are also available. Some practitioners prefer thinner mats, which allow them to feel more stable on the ground.
Adequate length and width. Most yoga mats are at least 24 inches wide and 68 inches long. Pricier mats may be slightly larger, and you can often pay more for widths up to 28 or 30 inches and lengths of roughly 80 inches or more -- nice if you're very tall or just appreciate a little extra room in a crowded yoga class.
A durable, easy-to-clean material. Synthetic materials such as PVC and TPE have a better reputation for durability than natural rubber, which is especially vulnerable if left in the sun for long periods. Most mats can be cleaned with a mild soap and water, but you'll want to follow any special manufacturer directions. Closed-cell mats, which repel moisture, are a bit easier to wipe and quicker to dry than open-cell mats, which absorb moisture.
An easy-to-grip surface. No one wants to slip around on their yoga mat, an especially important consideration when you're practicing hot yoga or vigorous styles such as Ashtanga. A slightly textured mat is usually easier to grip. If you want the stickiest option, look for a natural rubber mat with an open-cell surface. It will absorb sweat and moisture to stay as sticky as possible. Just note that you'll spend more time cleaning (and drying) this kind of mat to keep it hygienic.
Do you want an eco-friendly yoga mat? Many mats are made from PVC, or polyvinyl chloride. PVC is common in yoga mats because it's inexpensive to manufacture, durable, and easy to grip. However, PVC can contain heavy metals as well as phthalates -- questionable substances that have been linked to reproductive issues and other health concerns. The material also isn't recyclable, and can continue to release toxins once it ends up in a landfill. A much eco-friendlier option is natural rubber, but it might not be quite as durable. If you have a latex allergy, you can check out cotton or jute mats. Another option: TPE, or thermoplastic elastomer, which is a synthetic rubber that is biodegradable and recyclable.
Will you be traveling with your yoga mat? If so, look for a mat that is relatively lightweight -- 2 or 3 pounds at most -- that can be folded or rolled compactly. Keep in mind that foldable mats are easier to tote in luggage. Travel mats are typically thinner than other yoga mats, so don't expect a ton of cushioning.
Are you sensitive to smells? Many reviewers complain that yoga mats, especially natural rubber ones, tend to stink when they're new. It can take weeks for these smells to fade, so if you're bothered by strong odors, choose a synthetic material with a less pungent smell. You may also be able to help the smell dissipate by hanging the mat outside for a couple of days (avoid direct sunlight) or wiping it down with vinegar and water.
Do you want to use your yoga mat for Pilates or other classes, too? Many yoga mats can also be used for classes such as Pilates. For this purpose, experts suggest a firm and supportive yoga mat that has a thickness of at least 1/4 inch. This extra support is important since the class requires a good deal of hip and spine work. However, experts warn against using a Pilates mat for yoga, since Pilates mats aren't as slip-resistant, which could raise your risk of injury.
Do you care about the color of your mat? If you aren't picky, experts say you might be better off with a dark color simply because it will show less dirt, lint, or other wear and tear.