Thinx

Thinx'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 Thinx

The original name in period underwear and still one of the highest claimed capacities: one figure, "up to 12 regular tampons’ worth," for every current style, which we compute as about 108 mL. Sizing the brand itself pegs true to size, keyed to your hip. The most recognized brand, easy to find and widely reviewed.

Best for

Shoppers who want a widely available, high-capacity brand with one simple maximum instead of tier arithmetic.

Skip if

You want to buy by tier (Thinx publishes one figure, not a ladder), or a size run past 4X.

What stands out

Among the highest capacities here: its current styles claim “up to 12 regular tampons’ worth” and no millilitre figure, which we compute as about 108 mL
The most recognized brand - easy to find and widely reviewed

Trade-offs

One figure for every style, so there is no lighter tier to choose for light days
Smaller live catalog than the biggest brands here

Safety history: Thinx settled a PFAS marketing class action in 2023 without admitting wrongdoing. What that did and did not establish, and where testing stands: the PFAS guide.

How Thinx sizing runs

Thinx says its styles are completely true to size and to follow your hip measurement, measured at the widest point. By design they fit a little more snugly than regular underwear for leak protection, not undersized. The Teens line fits true to size and is narrower at the thigh.

Size	Hip	Waist
XS	35–36"	25–26"
S	37–38"	27–28"
M	39–40"	29–30"
L	41–42"	31–32"
XL	43–44.5"	33–34.5"
X (plus)	43–44"	36–37"
1X	45–47"	38–40"
2X	49–51"	42–44"
3X	53–55"	46–48"
4X	57–59"	50–52"

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

What Thinx's tiers claim, in millilitres

Note: Thinx gives one claim for its whole period line, 'up to 12 regular tampons' worth', and counts a regular tampon as 9 mL, so we show about 108 mL for every current style (computed from the claim, grade B).

Light (older tier name, no longer sold this way)9 mL Data quality grade B, converted from tampon counts
Moderate (older tier name, no longer sold this way)18–27 mL Data quality grade B, converted from tampon counts
Heavy (older tier name, no longer sold this way)36 mL Data quality grade B, converted from tampon counts
Super (older tier name, no longer sold this way)45 mL Data quality grade B, converted from tampon counts
All Day108 mL Data quality grade B, converted from tampon counts
All Night108 mL Data quality grade B, converted from tampon counts
Overnight (Teens)108 mL Data quality grade B, converted from tampon counts

Claims verified 2026-09-05 · Catalog checked 2026-10-04 · Millilitres are the brand's own published claims, normalized - methodology. Cross-brand view: the full table.

Thinx catalog (32)

Thinx

Everyday Comfort Hi-Waist

All Day· 108 mLData quality grade B, converted from tampon counts

Sizes XS–4X

$20

Our take on Thinx

How Thinx sizing runs

What Thinx's tiers claim, in millilitres

Thinx catalog (32)

The rest of the Thinx catalog (8)

Your size and tier at this brand