A beard grows about a millimeter every two or three days, depending on who you are—an eighth of an inch a week, on average. So testing beard trimmers can take a long time.

In general, we test each beard trimmer once a beard has grown out enough for a good trim—using at least two cutting lengths. Weight and balance matters, and so does the blade’s ability to get to the awkward areas around the neck. Our testers check how well-made and easy to use any attachments are, and we verify manufacturer claims about battery life and power. We also check in with professional haircutters, especially to verify claims of durability and reliability among brands and models.

Tester Andrew Williams has a relatively full beard, with straight-growing stubble. Tester Matthew Korfhage has coarse and angry hairs, with a seeming mind of their own. We’ve tried to reflect any possible issues—struggling with thick bristles, for instance—in our reviews, so you can be sure of the best possible trim with the least amount of effort.

Here’s some help on choosing the right features for your facial fuzz.

• Ceramic versus steel blades: Ceramic blades can hold their sharpness better than steel, but the smaller teeth of premium beard trimmer blades tend to be made of stainless steel.
• Barrel control: Some beard trimmers have on-device twist controls. For an easier life, pick one with minimal attachments.
• Ni-MH versus Li-ion: Avoid trimmers with excessively long charge times and those that use old nickel-metal-hydride batteries. They don’t hold their charge as long as lithium-ion.
• Waterproof? Beard trimming in the shower isn’t as beneficial as wet shaving, but a water-resistant design does let you wash your trimmer under the faucet with confidence.
• USB charging: It took far too long, but you can finally get USB charging cables for beard trimmers, while Manscaped even uses a USB-C on the shell itself. A major bonus for travel.
• Small versus larger teeth: Larger blade teeth can cut thick, dense hair, but smaller teeth allow for a closer, more precise cut. The latter is best exemplified by the Philips OneBlade family.
• Wide versus narrow blade: Hair trimmers have wider blades than beard trimmers. The narrower style provides greater control, with minimal time loss for those with shorter facial hair.
• Do blades need to be replaced? Use blade oil (often included) to avoid rusting, and blades should last for years. Trimmer-shaver hybrid Philips OneBlade models will need more regular replacing, though.
• Vacuum? Some beard trimmers have a vacuum feature, to avoid getting hair trimmings everywhere. In truth, it’s a bit of a gimmick.