The Best Period Underwear, Tested in Our Labs and by Real Users

Absorbency: Light (1 tampon's fluid) and Medium (3 tampons' fluid) | Sizes: XS–XXXXL | Care instructions: Machine wash cold and lay flat to dry. | Body material: 77% nylon, 23% Lycra Xtra Life | Gusset material: 86% cotton, 10% spandex, 4% carbon with inner 100% polyester layer | Return policy: Free returns within 30 days; can be worn and washed.

Testers were impressed with this pair's breathable nylon/Lycra material that felt just like regular underwear with a cotton gusset and a barely-there feel. This style is available in six nude shades to match a variety of skin tones and 15 other fun color and pattern options. We tested the lightest absorbency level, but this pair is now available in medium absorbency.

Lab results: This pair easily soaked up liquid at various angles and aced all of our Lab evaluations. These period panties showed no signs of wear after we laundered them multiple times, and GH analysts appreciated the lightweight fabric similar to athletic wear that stays hidden under clothes without panty lines.

Tester notes: Testers were surprised by how thin the pad was, and one said that these are the "perfect backup to tampons on heavier flow days." They're also ideal for lighter days on their own. Another tester said they were "the most comfortable period underwear I've ever tried." Another especially liked that they were "soft and stretchy and not bulky."

RELATED: The Best Menstrual Cups

Absorbency: Medium (4 tampons' fluid) | Sizes: XXS–3X | Care instructions: Machine wash and tumble dry low or air dry. | Body material: 95% rayon, 5% spandex | Gusset material: Not listed | Return policy: Depends on size

Period panties can get expensive, but this pair is more affordable and a popular choice on Amazon. Plus, they have free two-day shipping for Prime members in case you need them quickly and free returns within 30 days. There's a leakproof barrier that extends from the front all the way through the back. Note that this style is available only in black, but it has mesh detailing on the sides.

Lab results: This pair washed beautifully with no shrinkage or changes in appearance after five wash cycles. The absorbent core proved to be decently absorbent, though when the pair was held at an angle, it showed more leaks than other tested styles. Just note that these claim to be made with "bamboo fabric," which is really rayon.

Tester notes: Testers liked wearing this period underwear instead of pads, with one calling them "hassle-free." A different tester said, "These don't feel bulky and I didn't worry about leaking," while another noted, "The fabric was nice and smooth." Multiple testers reported that this pair ran small and opted to size up.

RELATED: The Best Menstrual Discs

Absorbency: Medium (3 tampons' fluid) and Heavy (5 tampons' fluid) | Sizes: XS–4X | Care instructions: Machine wash cold and lay flat to dry. | Body material: 84% polyamide, 16% elastane | Gusset material: 95% cotton, 5% elastane with polyester and PU liner | Return policy: Free returns on Amazon

Thinx is probably the most popular brand on this list, and that's for two good reasons: Its marketing campaigns are everywhere and our testers loved the product. One user thought they would never find period panties that were stylish, comfortable and functional — until they tested a pair of Thinx. With chic lace detailing, this pair stayed in place.

Lab results: We applied our test fluid at an angle, and the absorbent core quickly trapped it with minimal runoff. The underwear showed no signs of wear after laundering, and the mesh detailing stayed in prime condition. The liner was also mostly made of cotton.

Tester notes: Multiple testers were especially impressed with this pair's impressive absorbency. One tester said this pair was "absorbent and didn't leak at all." Another tester reported, "They really stayed in place which gave me more confidence than another pair I tried." However, some testers noted that the band was a bit snug.

Absorbency: Light (2 tampons' fluid) | Sizes: 5–10 | Care instructions: Machine washable and dryer safe | Body material: 87% polyester, 13% spandex | Gusset material: 100% polyester | Return policy: Free returns on Amazon

Period underwear can be costly, but this affordable pack from Hanes includes three pairs for just $16. Available as a bikini or brief, this underwear offers light protection to be worn alongside other menstrual products. The brand's size chart is a bit confusing, but they should fit wearers of women's size 4–20.

Lab results: Designed for light protection, this pair was not as absorbent as other pairs in our evaluation. The built-in pad is wide with a snug fit around the legs to offer ample coverage. We did notice some loose threads and stitches in our evaluation.

Tester notes: Testers liked the "classic fit" and simple, no-frills design. Our testers tried the brief style and liked that it offered full coverage without digging in, but a few gave it low appearance scores. The material was lightweight and breathable, according to testers.

Absorbency: Heavy (5 tampons' fluid) | Sizes: XS–4X | Care instructions: Machine wash cold and then hang to dry. | Body material: 96% modal, 4% elastane | Gusset material: 100% polyester with PU liner | Return policy: The brand offers a 45-day trial on all orders, saying "if you’re unhappy with your purchase, we’ll try to make it right."

If you don't like the look of typical period underwear, you may love this overnight option. It looks just like loose shorts from the outside, but this pick from Thinx has super-absorbent built-in period underwear for the ultimate loungewear.

Lab results: The shorts feature a larger pad that absorbed fluid quickly held onto it, showing no leaks during testing. The pair didn't shrink after laundering either — GH analysts also noted that the fabric stayed just as soft after multiple cycles.

Tester notes: Testers loved that they "offered excellent protection while looking like a typical pair of sleep shorts." Saying that the outer fabric is "super soft," multiple testers noted that the pad is on the bulky side and best for heavy flow days.

Absorbency: Heavy (8 tsp fluid) | Sizes: 3XS–6XL | Care instructions: Machine wash cold in a mesh bag; line dry overnight. Avoid machine drying. | Body material: 95% cotton, 5% spandex | Gusset material: 89% polyester, 11% spandex | Return policy: Free returns for used first-time underwear orders from TomboyX; future orders can be returned unused and unwashed within 30 days.

This style from TomboyX has the most inclusive size range out of all the styles we tested — from 3XS to 6XL. Our pros love that this brand features a variety of gender-inclusive options too.

Lab results: With a long liner and wide waistband, this pair stayed in place securely and absorbed fluid quickly in our tests. GH analysts also note that the full coverage design would be great to use as overnight protection.

Tester notes: Made with a cotton/spandex blend, several testers said the "fabric was super soft." One tester shared that it's "high wasted [and] comfortable and I felt confident with the protection it was providing." While some testers noted this option was bulky and visible under some clothing items, they especially appreciated its high absorbency when worn at home or overnight.

Absorbency: Heavy (8 tampons' fluid) | Sizes: XXS–XXL (Teen sizing) | Care instructions: Machine wash cold and lay flat to dry or tumble dry low. | Body material: 70% nylon, 30% spandex | Gusset material: 100% polyester, PU Film| Return policy: Your first order has a 30-day return period for one worn product. Future underwear products cannot be returned.

Your first period can be exciting but overwhelming too. Knixteen provides comfy options that can make this new stage easier for tweens so they can worry less about leaks. Also available in light and medium absorbencies, this best-selling super-absorbency bikini style offers ample coverage and is available in a variety of 17 fun shades in a breathable material.

The brand also offers a starter set with two pairs of underwear and sleep shorts. Because this pick features teen sizing (which is inconsistent from brand to brand), some online reviewers found it tougher to find the best size for them.

Lab results: The brand's original leakproof underwear aced Lab evaluations for quickly absorbing fluid at a variety of angles without leaking. The sleep shorts have a much larger pad for full coverage that also held onto an impressive amount of fluid in our test.

Tester notes: In our extensive testing of period underwear, Knix styles continue to be top performers. "They have held out on her heaviest days and she absolutely loves them," said one online reviewer about her 11-year-old daughter. "So grateful for this fantastic solution for my little one." Another online reviewer said her 13-year-old daughter "goes all day at school without anxiety and leaks. Phenomenal." She even added, "Where were these when I was in middle school and high school?"

RELATED: The Best Period Swimwear

Absorbency: Light (1 tampon's fluid) | Sizes: XS–2XL | Care instructions: Machine wash cold and hang dry. | Body material: 62% polyamide, 38% Lycra Xtra Life elastane | Gusset material: 100% polyester | Return policy: Your first order has a 30-day return period for one worn product. Future underwear products cannot be returned.

Featuring seamless construction with silky, stretchy materials, Saalt's period thongs look and feel just like everyday underwear. It's perfect to wear under leggings or other form-fitting clothing to avoid any panty lines.

Lab results: The discreet liner absorbed fluids well and held onto them to keep you dry. The liner is smaller than other underwear styles, so it did show some leakage during our evaluations. This pair is best to be worn as backup protection or on very light days.

Tester notes: Testers especially loved the thinness of Saalt period underwear and agreed that they should be worn alongside other menstrual products. One tester said, "This thong feels like my favorite lingerie while giving me peace of mind during my period."

Absorbency: Heavy (8+ tampons' fluid with removable insert; 4 tampons' fluid without) | Sizes: XXS–5X | Care instructions: Rinse out in cool water, then wash and dry with your regular laundry. | Body material: 48% TENCEL lyocell, 48% organic cotton, 4% spandex | Gusset material: 90% Truetex™ (88% recycled polyester, 12% organic cotton), 10% TPU | Return policy: First time orders can be returned used within 60 days. Future orders can be returned unused and unwashed within the 60-day return window (these products are then donated).

Aisle period underwear works a bit differently than the other picks on this list. The period underwear has a thin built-in liner for light absorbency, but you can add the included removable insert on heavier days. (Extra removable pads are sold separately.) It feels more similar to wearing a pad with your underwear. The comfy boxer design is made using sustainable materials like Tencel and organic cotton.

Lab results: The pad quickly absorbed fluid and held onto it, showing only minimal runoff leaks on the sides. GH analysts appreciated that this style is available in sizes XXS–5X.

Tester notes: Not all of our testers liked the concept, but they still found them comfortable to wear with several noting they had a "soft feel." Multiple testers did note leaks.