Knix

Knix's sizing and absorbency, translated onto the same scale as every other brand - so you can shop it (or leave it) with a fair comparison.

Our take on Knix

The mainstream heavyweight: the widest catalog we track and the highest verified capacity tier, at prices spanning budget multipacks to premium. The catch is a PFAS settlement in its history, so check its current testing.

Best for

Shoppers who want the most choice and genuinely high capacity from a familiar US brand with frequent sales.

Skip if

You are specifically avoiding brands with a PFAS history, or you want the lowest possible price.

What stands out

Highest verified capacity tier of any brand here (Ultra, up to about 99 mL)
The largest live catalog we track - 100+ styles across cuts and absorbencies
Wide price range, with inexpensive multipacks alongside premium styles

Trade-offs

Settled a $1.4M PFAS class action and agreed to drop unsupported "PFAS-free" claims (see the note above)
Its leakproof styles are widely reported to run small, so size up
So many styles that narrowing down takes some filtering

Knix and PFAS: an honest note

Knix settled a class action for $1.4 million over PFAS-related marketing, and agreed to stop calling its products "PFAS-free," "toxic-chemical-free," or "fluorine-free" without support, plus two years of increased PFAS testing. Knix did not admit wrongdoing.

What the lawsuits and testing did and did not establish

How Knix sizing runs

Brand labels core styles "True to Size" on product pages (e.g. Essential High Rise). However, customer reviews consistently report the leakproof styles run small / recommend sizing

Size	Hip	Waist
S	33–37"	23–27"
M	38–41"	28–31"
L	42–44"	32–34"
XL	45–47"	35–37"
XXL (2X)	48–50"	38–40"
XXXL (3X)	51–53"	41–53"
XXXXL (4X)	54–56"	26"+

Know your hip measurement? Get your size in every brand at once.

What Knix's tiers really hold

Heads up: Knix's blog and live collection pages publish different super-tampon counts per tier; this table uses the live collection-page (higher) figures.

Light5–15 mL Data quality grade B, converted from tampon counts
Moderate18–36 mL Data quality grade C, conflicting / unconfirmed claim
Heavy36–63 mL Data quality grade C, conflicting / unconfirmed claim
Ultra63–99 mL Data quality grade C, conflicting / unconfirmed claim

Claims verified 2026-06-11 · Millilitres are the brand's own published claims, normalized - methodology. Cross-brand view: the full table.

Knix catalog (187)

40% off

Knix

Light Leakproof No-Show Thong - Last Call

Light· 5–15 mLData quality grade B, converted from tampon counts

Sizes XXL–XXXXL

$15$25

Our take on Knix

How Knix sizing runs

What Knix's tiers really hold

Knix catalog (187)

Light Leakproof No-Show Thong - Last Call

Light Leakproof No-Show Mesh Thong - Last Call

Super Leakproof® Cotton Boxer Brief - Last Call

Light Leakproof No-Show Mesh Bikini - Last Call

Light Leakproof No-Show Mesh Boyshort - Last Call

Light Leakproof Lace Bikini - Last Call

Light Leakproof Luxe Modal Bikini - Last Call

Teen Light Leakproof No-Show Bikini - Last Call

Teen Leakproof UltraThin No-Show Thong - Last Call

Light Leakproof No-Show Bikini - Last Call

Light Leakproof No-Show French Cut - Last Call

Leakproof UltraThin No-Show French Cut - Last Call

Teen Super Leakproof® No-Show Boyshort - Last Call

Leakproof UltraThin No-Show Bikini - Last Call

Teen Super Leakproof® No-Show Bikini - Last Call

Light Leakproof UltraThin No-Show Thong - Last Call

Light Leakproof No-Show High Rise - Last Call

Super Leakproof® No-Show Thong - Original - Last Call

Super Leakproof® No-Show French Cut - Original - Last Call

Super Leakproof® No-Show Bikini - Original - Last Call

Super Leakproof® No-Show Boyshort - Original - Last Call

Ultra Leakproof Zones+® Bikini - Last Call

Teen Light Leakproof No-Show Bikini 2-Pack - Last Call

Teen Light Leakproof No-Show Boyshort 2-Pack - Last Call

Leakproof UltraThin No-Show High Rise - Last Call

Teen Leakproof Luxe Modal Sleep Boxer - Last Call

Leakproof UltraThin No-Show Boybrief - Last Call

Teen StageProof™ Leakproof UltraThin Underwear

Light Leakproof No-Show Thong

Light Leakproof No-Show Bikini

Super Leakproof® No-Show High Rise - Original - Last Call

Teen Super Leakproof® No-Show Boyshort 2-Pack - Last Call

Teen Super Leakproof® No-Show Boyshort

Light Leakproof UltraThin Thong

Teen Super Leakproof® No-Show Bikini

Leakproof Cotton High Rise

Super Leakproof Cotton Bikini

Teen Super Leakproof® Sleepover Short - Last Call

Super Leakproof® Dream Short™ - Original - Last Call

Super Leakproof® Dream Short™ - Last Call

Leakproof UltraThin Mesh High Rise

Teen SuperPlus Leakproof® No-Show Bikini

Leakproof UltraThin Boybrief

Teen Period Emergency Kit - Boyshort

Teen Period Emergency Kit - Bikini

Teen Super Leakproof® Sleepover Short

Light Leakproof No-Show Thong 3-Pack - Last Call

Light Leakproof No-Show Bikini 3-Pack - Last Call

Teen Light Leakproof No-Show Boyshort 3-Pack - Last Call

Light Leakproof No-Show Bikini 3-Pack - Last Call

Light Leakproof No-Show Thong 3-Pack - Last Call

Light Leakproof No-Show Bikini 3-Pack - Last Call

Teen Light Leakproof No-Show Bikini 3-Pack - Last Call

Teen SuperPlus Leakproof® Sleepover Short

Teen Super Leakproof® Mini Sleepover Boxer

Pursuit Leakproof Training Short - Last Call

Teen Leakproof UltraThin No-Show Boyshort 3-Pack - Last Call

Teen Leakproof UltraThin Bikini Holiday 3-Pack - Last Call

Teen Leakproof UltraThin No-Show Bikini 3-Pack - Last Call

Leakproof UltraThin No-Show Bikini 3-Pack - Last Call

Super Leakproof® Mini Dream Boxer

SuperPlus Leakproof® Dream Short

Leakproof Thigh Saver® 10” - Gift with Purchase

Super Leakproof® No-Show Boyshort 3-Pack - Original - Last Call

Super Leakproof® No-Show Bikini 3-Pack - Original - Last Call

Teen Super Leakproof® No-Show Boyshort 3-Pack - Last Call

Leakproof UltraThin No-Show High Rise 3-Pack - Last Call

Teen Super Leakproof® No-Show Bikini 3-Pack - Last Call

Super Leakproof® Dream Short™ 2-Pack

Teen Super Leakproof® No-Show Bikini 3-Pack

Super Leakproof® No-Show High Rise 3-Pack

Super Leakproof® No-Show Bikini 3-Pack

Teen Super Leakproof® No-Show Boyshort 3-Pack

SuperPlus Leakproof® Dream Short 2-Pack

Teen Leakproof Starter Kit - Bikini

Teen Leakproof Starter Kit - Boyshort