5 Best Long Underwear of 2026: Tested for Women's Comfort

A comparison-first guide to long-leg women’s boxers, women’s boxer shorts, bamboo underwear for women, and anti chafe underwear.

 

If you’re searching for the best long underwear, you’ll quickly notice a problem: most guides mean thermal long johns. This article focuses on the everyday version—long-leg women’s underwear (usually 6–12 inches of inseam) that acts like a comfort base layer: reduces inner-thigh friction, stays put under clothes, and feels good for long wear.

 

Our top pick is Flissie’s 9" bamboo women’s boxers, and we compare it directly against popular long-leg alternatives (including Woxer, Thigh Society, Chaffree, and TomboyX). Where relevant, we also call out other long-leg options you may want to consider.

 

Key takeaways

• Best overall for everyday comfort + anti-chafe coverage: Flissie 9" bamboo women’s boxers [1][2]
• Best hot-weather ‘barely-there’ slip short: Thigh Society The Cooling 9" [6]
• Best classic boxer-brief feel: Woxer Biker 9" [4][5]
• Best inclusive cotton-stretch 9" option: TomboyX 9" Boxer Briefs [9]
• Best budget-friendly performance anti-chafe short (UK sizing range): Chaffree KnickerBoxers (8" long option) [8]

 

Quick comparison table

 

How we tested (comfort-first scorecard)

We didn’t run lab tests, and we’re not claiming medical outcomes. Instead, we evaluated each product using a practical scorecard focused on the things that actually affect women’s comfort in long-leg underwear:

 

1.       Anti-chafe coverage and stay-put leg length (inseam and anti-roll construction cues)

2.       Fabric performance for real life (breathability, moisture handling, temperature comfort)

3.       Under-clothes behavior (rolling, riding up, visible lines, waistband comfort)

4.       Sizing and inclusivity (size range, clear fit guidance, stretch)

5.       Care and longevity signals (wash guidance, fabric blends)

6.       Trust cues and transparency (clear labeling, certifications, clear policies)

 

For friction issues (chafing), medical guidance consistently emphasizes reducing moisture and friction—moisture-wicking fabrics and barrier strategies help. [10][11]

 

The 5 best long underwear picks for women in 2026

These picks are intentionally long-leg. If you only need a short boyshort, you’ll likely want a different guide.

 

1) Flissie 9" bamboo women’s boxers (Tanboocel bamboo viscose) - Best overall

 

If you want long underwear that behaves like real underwear (not shapewear), Flissie’s 9-inch women’s boxer shorts are built around one job: comfortable, stay-put thigh coverage that helps reduce friction under everyday outfits. The fabric is bamboo viscose (Tanboocel) with brand claims around breathability, moisture-wicking, and temperature regulation for warm and cool weather. [1][2][12][13]

 

Links: Flissie women's boxers | Size guide | How to care for bamboo underwear | Anti-chafing underwear guide

 

Why we picked it:

·       Long 9" inseam for more inner-thigh coverage (Flissie positions 9" as the best option for chafing and roll-up). [1]

·       Fabric is listed as 95% bamboo (Tanboocel) with elastic in the waistband for a flexible hold. [1]

·       Flissie describes the bamboo fabric as light, airy and temperature regulating—comfortable in both warm and cool weather (helpful if you want a lightly warming base layer feel without overheating). [2]

·       Clear care guidance (cool wash, air dry), which supports longevity if you follow it. [1][17]

 

Pros:

·       Excellent anti-chafe coverage for dresses, jeans and leggings. [1]

·       Soft feel + breathable positioning for day-long wear and sleep/lounging. [2]

·       Temperature-regulating claim = year-round comfort angle. [2]

·       Clear care instructions (20C wash, air dry). [1]

 

Cons / considerations:

·       Not thick thermal long underwear; think comfort base layer, not insulation. [2]

·       Many ‘bamboo’ textiles are viscose/rayon made from bamboo (labeling nuance). [12][13]

 

Key specs (quick):

·       Length options: 6" and 9" inseam options are advertised; this guide focuses on 9". [1]

·       Fabric: 95% bamboo (Tanboocel); elastic in waistband. [1]

·       Care: 20C cool wash; no tumble dry; air dry only. [1]

·       Sizing: Use the size guide to choose fit. [20]

 

Best for: Women searching ‘best long underwear’ but wanting long-leg women’s boxers that feel like underwear, deliver anti chafe underwear benefits, and use bamboo underwear for women comfort cues.

 

2) Woxer Biker 9" - Best classic boxer-brief feel

Woxer’s Biker is a popular 9-inch women’s boxer short / boxer brief for people who want a more traditional boxer-brief structure: a familiar waistband, paneling that stays put, and a smooth feel that works under clothes. [4][5]

 

Links: Product page | Fabric guide

Why we picked it:

·       The Biker is marketed as a 9" boxer brief. [4]

·       Woxer’s fabric guide lists their core Modal as 95% modal and 5% elastane, positioned as breathable and moisture-wicking. [5]

·       A good option if you want women’s boxer shorts that feel a bit more ‘structured’ than a slip short.

 

Pros:

·       9" inseam gives strong anti-chafe coverage for walking and commuting. [4]

·       Modal hand-feel is very soft; elastane adds stretch for movement. [5]

·       Often a good bridge between underwear and light base layer feel.

 

Cons / considerations:

·       Modal can feel warmer than ultra-sheer slip shorts in very hot weather (depends on you).

·       If you specifically want bamboo underwear, this one is modal (beechwood-based). [5]

 

Key specs (quick):

·       Length: 9" inseam. [4]

·       Fabric (core modal): 95% modal, 5% elastane (per fabric guide). [5]

 

Best for: People who want women’s boxers with a classic boxer-brief feel and a reliable 9" inseam for anti-chafe coverage.

 

3) Thigh Society The Cooling 9" - Best for hot weather under dresses

Thigh Society’s Cooling 9 is a slip-short style designed to reduce friction while staying extremely light. It’s a great ‘under dresses’ option when you want long-leg coverage without compression. [6][7][10][11]

 

Links: Product page | OEKO-TEX Standard 100

 

Why we picked it:

·       The Cooling 9 is positioned as the lightest, cooling slip short with sheer coverage. [6]

·       The product page lists the fabric blend and states the components are OEKO-TEX STANDARD 100 certified, with testing details shown on-page. [6][7]

·       If heat + sweat drives your chafing, reducing moisture and friction is a key strategy. [10][11]

 

Pros:

·       Very lightweight and cool-to-the-touch feel. [6]

·       Long 9" coverage helps prevent thigh rub under dresses and skirts. [6]

·       OEKO-TEX STANDARD 100 is a textile safety label (tested for harmful substances). [7]

 

Cons / considerations:

·       Sheer coverage may not be everyone’s preference. [6]

·       More ‘slip short’ than everyday underwear - depends what you want under your outfit.

 

Key specs (quick):

·       Length: 9" coverage option. [6]

·       Fabric & care: 78% Sensil Breeze nylon, 20% elastane, 2% cotton; machine wash cold; tumble dry low (as listed). [6]

·       Certification: OEKO-TEX STANDARD 100 certified components (as stated). [6][7]

 

Best for: Hot-weather anti chafe underwear needs (especially under dresses) when you want minimal bulk and no compression.

 

4) Chaffree KnickerBoxers (8" long) - Best budget-friendly performance anti-chafe short

Chaffree’s KnickerBoxers are purpose-built anti-chafing shorts with an 8-inch long option. They lean more ‘functional base layer’ than luxury underwear, but the positioning is extremely clear: reduce sweat + friction. [8][10][11]

 

Links: Product page

 

Why we picked it:

·       Chaffree lists short (6") and long (8") leg lengths and positions the fabric as quick-drying and moisture-wicking (COOLMAX). [8]

·       Keeping skin drier is one of the most consistent prevention tips for chafing. [10][11]

·       UK size range is unusually broad on the listing. [8]

 

Pros:

·       Clear anti-chafe purpose, with a long-leg option. [8]

·       Performance fabric positioning can help on sweaty days. [8][10]

·       Great extended size range per the product listing. [8]

 

Cons / considerations:

·       More ‘active base layer’ look/feel than ‘luxury underwear’ (set expectations).

 

Key specs (quick):

·       Leg lengths: 6" and 8" options. [8]

·       Fabric positioning: COOLMAX moisture-wicking, quick-drying claims. [8]

 

Best for: Budget-conscious shoppers who want anti chafe underwear with performance fabric positioning and a longer inseam.

 

5) TomboyX 9" Boxer Briefs - Best inclusive cotton-stretch 9" option

TomboyX’s 9-inch boxer briefs are a strong pick if you want a classic cotton-stretch feel, flatlock seams, and a brand that explicitly builds for a wide range of bodies. [7][9][10][11]

 

Links: Product page | OEKO-TEX Standard 100

 

Why we picked it:

·       The product page lists a 9" inseam and 95% OEKO-TEX certified cotton with 5% spandex. [9]

·       Flatlock seams are called out as smooth and durable. [9]

·       OEKO-TEX certification is a textile safety signal (tested for harmful substances). [7][9]

 

Pros:

·       Classic cotton-stretch feel for everyday wear. [9]

·       9" inseam = reliable thigh coverage. [9]

·       Flatlock seams can reduce irritation from rubbing. [9]

 

Cons / considerations:

·       Cotton can hold moisture more than performance blends - if you sweat heavily, consider bamboo viscose or synthetics for workouts. [10][11]

 

Key specs (quick):

·       Length: 9" inseam. [9]

·       Fabric: 95% OEKO-TEX certified cotton, 5% spandex. [9]

·       Care: Machine wash cold; tumble dry low (as listed). [9]

 

Best for: Women who want women’s boxer shorts with a classic cotton feel and a clear 9" inseam rather than a sheer slip short.

 

Buyer’s guide: how to choose the best long underwear for women

When long underwear equals ‘long-leg underwear,’ comfort comes down to three things: length, fabric, and construction. Here’s how to choose quickly:

 

1) Choose inseam length based on where you chafe

·       6 inches: mid-thigh coverage; good for most skirts and summer outfits.

·       9 inches: the most versatile anti-chafe length; more coverage means less skin-on-skin friction.

·       12 inches+: maximum coverage; great for long walks, travel days, or if you chafe lower on the thigh.

 

2) Match fabric to your climate and activity

For chafing, reducing moisture and friction is key. Moisture-wicking clothes and anti-friction strategies are common recommendations. [10][11]

·       Bamboo viscose (often labeled viscose/rayon made from bamboo): soft, breathable feel; many people like it for year-round comfort. [1][2][12]

·       Modal: very soft and smooth; great daily comfort with good stretch. [4][5]

·       Performance nylon/elastane blends: often coolest for hot weather and high sweat. [6][10]

·       Cotton-stretch: classic feel; comfy, but may hold more moisture if you sweat heavily. [9][10]

 

3) Construction cues that reduce ride-up and irritation

·       Stay-put leg openings (not too loose; not too tight).

·       Smooth seams or flatlock seams if you’re sensitive to rubbing. [9]

·       A waistband that doesn’t roll or dig in (especially for sitting all day).

 

Bamboo underwear for women: temperature regulation, warmth, and the labeling reality

Bamboo underwear has a reputation for feeling ‘cool in heat’ and ‘comfortable in cool weather.’ In practice, breathable fabric that manages moisture can help you feel less clammy, which matters when it’s chilly. Flissie explicitly describes its bamboo underwear as light and temperature regulating for both warm and cool weather. [2]

 

The nuance: the U.S. Federal Trade Commission explains that many ‘bamboo’ textiles are actually viscose/rayon made from bamboo, and labeling should reflect that (e.g., ‘viscose made from bamboo’). This doesn’t automatically make the fabric bad—it’s often extremely soft—but it does matter for transparency and sustainability claims. [12][13]

 

Other long-leg options you may want to consider (not in the top 5)

These are popular alternatives with long-leg coverage, but they didn’t make this top 5 because they either target a narrower use-case or don’t match the underwear-first feel we prioritised:

 

·       Snag Tights Chub Rub Shorts - Long anti-chafing shorts positioned around eliminating thigh rub, with ‘cooling technology’ claims. [14]

·       Jockey Skimmies - A well-known slipshort category designed to smooth and reduce chafe under clothes. [15]

·       Woxer Biker Flex (active) - A 9" inseam active underwear version positioned as sweat-wicking and supportive (recycled fabric). [16]

 

FAQs

What is the best long underwear for women in 2026?

If ‘long underwear’ means long-leg women’s underwear for comfort and chafing, Flissie’s 9" bamboo women’s boxers are a strong overall pick for soft feel, long inseam coverage and year-round comfort positioning. [1][2]

 

Are women’s boxers good for chafing?

Yes. Longer inseams reduce skin-on-skin friction. Pair that with moisture management and you’re addressing the two biggest chafe drivers: friction and moisture. [10][11]

 

Does bamboo underwear keep you warm?

Bamboo viscose isn’t thick insulation like thermal long johns. But breathable, moisture-managing fabric can help you feel more comfortable in cool weather by reducing the damp, clammy feeling that can make you feel chilly. Flissie also describes its bamboo fabric as temperature regulating for both warm and cool weather. [2]

 

Which fabric is best for anti chafe underwear?

For sweaty conditions, moisture-wicking performance fabrics and lightweight tech blends can help. For everyday comfort, many people like bamboo viscose or modal for softness plus breathability. Medical guidance supports reducing moisture and friction as core prevention strategies. [10][11]

 

How do I stop long-leg underwear from rolling up?

Choose a longer inseam (9" helps), ensure the leg opening isn’t too loose, and look for stay-put construction cues (good stretch recovery and waistbands that don’t roll).

 

How should I wash bamboo underwear for women?

Follow the brand’s care label. Flissie advises cool washes and air drying on the product page, and their care guide recommends cold water (30C or below) and avoiding harsh detergents/fabric softeners for longevity. [1][17]

 

Other Flissie guides that might help

·       Anti-chafing underwear guide (what actually works)

·       How to care for bamboo underwear (washing + longevity)

·       Why women’s boxers work under dresses

·       How to prevent and remove thigh chafing

·       Women’s boxers size guide

 

Websites used in this guide

·       Woxer Biker 9"

·       Thigh Society The Cooling 9"

·       Chaffree KnickerBoxers

·       TomboyX 9" Boxer Briefs

·       FTC bamboo textiles guidance

·       FTC consumer advice on 'bamboo' fabrics

·       Cleveland Clinic: chafing causes + prevention

·       Cleveland Clinic: tips to prevent chafing

·       OEKO-TEX Standard 100

References

[1] Flissie. Women's Bamboo Boxers | Anti-Chafe Boxer Shorts UK (product page). https://www.flissie.com/products/bamboo-womens-boxers (accessed 13 Feb 2026).

[2] Flissie. Bamboo Women's Boxers UK | Premium Bamboo Underwear (site page; temperature regulation, moisture-wicking claims). https://www.flissie.com/ (accessed 13 Feb 2026).

[3] Flissie. Women's Bamboo Boxers (why bamboo / Tanboocel claims). https://www.flissie.com/pages/womensboxers (accessed 13 Feb 2026).

[4] Woxer. Biker Black - 9" boxer brief (product page). https://woxer.com/en-uk/products/biker-black (accessed 13 Feb 2026).

[5] Woxer. Woxer Fabric Guide (modal composition). https://woxer.com/pages/woxer-fabric-guide (accessed 13 Feb 2026).

[6] Thigh Society. The Cooling 9" Black (product page; fabric & OEKO-TEX info). https://www.thighsociety.com/products/cooling-9-black (accessed 13 Feb 2026).

[7] OEKO-TEX. OEKO-TEX STANDARD 100 (what the label means). https://www.oeko-tex.com/en/our-standards/oeko-tex-standard-100/ (accessed 13 Feb 2026).

[8] Chaffree. Womens KnickerBoxers - Anti Chafing Shorts (product page). https://www.chaffree.com/product/womens-knicker-boxers/ (accessed 13 Feb 2026).

[9] TomboyX. 9" Boxer Briefs - X= Black (product page). https://tomboyx.com/products/9-boxer-briefs-x-black (accessed 13 Feb 2026).

[10] Cleveland Clinic. Chafing: Causes, Treatment & Prevention. https://my.clevelandclinic.org/health/diseases/23517-chafing (accessed 13 Feb 2026).

[11] Cleveland Clinic. Skin Protection: Tips To Prevent Chafing. https://health.clevelandclinic.org/prevent-chafing (accessed 13 Feb 2026).

[12] Federal Trade Commission. Bamboo Textiles (labeling guidance for businesses). https://www.ftc.gov/bamboo-textiles (accessed 13 Feb 2026).

[13] Federal Trade Commission. 'Bamboo' Fabrics (consumer advice). https://consumer.ftc.gov/bamboo-fabrics (accessed 13 Feb 2026).

[14] Snag Tights. Chub Rub Shorts (collection page). https://snagtights.com/collections/all-chub-rub-shorts (accessed 13 Feb 2026).

[15] Jockey. Skimmies Collection (anti-chafing slipshorts). https://www.jockey.co.uk/collections/skimmies (accessed 13 Feb 2026).

[16] Woxer. Biker Flex Black (active 9" inseam; product page). https://woxer.com/products/bikerflex-black (accessed 13 Feb 2026).

[17] Flissie. How to Care for Bamboo Underwear: Expert Tips to Double Their Lifespan (blog). https://www.flissie.com/blogs/all-blogs/how-to-care-for-bamboo-underwear-expert-tips-to-double-their-lifespan (accessed 13 Feb 2026).

[18] Flissie. Anti-Chafing Underwear Guide: What Actually Works for Women (blog). https://www.flissie.com/blogs/all-blogs/anti-chafing-underwear-guide-what-actually-works-for-women (accessed 13 Feb 2026).

[19] Flissie. Why Womens Boxers are Perfect Under Summer Dresses (blog). https://www.flissie.com/blogs/all-blogs/why-womens-boxers-are-perfect-under-summer-dresses (accessed 13 Feb 2026).

[20] Flissie. Size Guide (fit & sizing resource). https://www.flissie.com/pages/size-guide (accessed 13 Feb 2026).

[21] Flissie. How to Prevent and Remove Thigh Chafing (blog). https://www.flissie.com/blogs/all-blogs/how-to-prevent-and-remove-thigh-chafing-chub-rub-free-summer (accessed 13 Feb 2026).