Absorbency Guide: How to Find the Right Period Underwear for Your Flow

March 22, 2024
Team Knix

Just like us, our products are constantly evolving. Launching a whole new period care category over a decade ago was no easy feat—and neither is challenging ourselves to innovate and redefine those same products everyday

With the launch of Leakproof UltraThin No-Show underwear, we’re changing the period game (again) with new products and absorbencies that feel more lightweight than ever. This is all, of course, with the aim of helping you feel uninhibited on your period, so you can live unapologetically free (from bulky underwear). 

Whether you’re a period underwear enthusiast or novice, we’re here to help you find the best period underwear for your lifestyle and flow. Ahead is everything you need to know about our new absorbency classifications and which styles best suit whatever phase of life you're in. 

Oh, and psst, if the packaging on your glossy new undies doesn’t totally match up to this guide—don’t worry, we’re working on that. 

Lightest Absorbency 🩸

Knix model wearing Light Leakproof Lace High Rise underwear in Rose Water display: full

For your lightest period days—you know, when you’re spotting and kind of just want to forget you’re on your period altogether—there’s Light Leakproof No-Show Underwear. This range is designed to be your best friend on light flow days and can be worn with tampons and menstrual cups as backup leak protection. To that we say: go ahead and wear the white pants. 

Absorbency: Absorbs 1 to 1.5 tsps of menstrual fluid, discharge, and sweat—which is about the equivalent of 0.5-1 regular tampon

Styles: Light Leakproof No-Show BikiniBoyshortHigh RiseThongHigh Rise ThongCheeky, and Mesh Thong.

Best for: Wearing solo when you’re spotting, backup protection on regular flow days, and mildly sweaty workouts. 

Light Absorbency 🩸🩸

Knix model wearing Light Leakproof No-Show French Cut underwear in Rose Water display: full

Among our Light Leakproof assortment are slightly more absorbent underwear styles that can be worn in combination with tampons and menstrual cups as backup protection on regular flow days—or on their own on days when you’re wondering hmm…is my period actually over or am I still spotting? 

Absorbency: Absorbs 1.5-3 tsps of menstrual fluid, discharge, and sweat—which is about the equivalent of 1-3 regular tampons.

Styles:

Best for: Your first time trying period underwear, wearing as backup protection (with a tampon or menstrual cup), days when you’re spotting, working up a sweat. 

Medium Absorbency 🩸🩸🩸

Knix model wearing Leakproof UltraThin No-Show Bikini underwear in Warm Sand display: full

Looking for more than just backup protection? For regular flow days, there’s period underwear that can be worn solo all-day long (or as a backup when your flow is heavier). If you want all the absorbency but none of the bulk, opt for the newest Leakproof UltraThin No-Show styles. 

Absorbency: Absorbs 3-6 tsps worth of menstrual fluid, sweat, and urine—which is about the equivalent of 2-3 super tampons.

Styles:

Best for: Wearing solo on medium flow days, backup protection on heavy flow days, and light bladder leaks. 

Heavy Absorbency 🩸🩸🩸🩸

Knix model wearing the Super Leakproof Dream Short in Black display: full

If we had a dime for every time we soaked through bedsheets or our favorite pair of pants, our bank accounts would all have an extra comma. Super Leakproof period underwear styles were designed with heavier flow days in mind—because who wants to wake up early to change their tampon? 

Absorbency: Absorbs 6-11 tsps of menstrual fluid, sweat, and urine—which is about the equivalent of 3-6 super tampons.

Styles:

Best for: Your period’s heavier days, overnight protection for sweet dreams, and sneaky bladder leaks when you cough or sneeze.

Ultra Absorbency 🩸🩸🩸🩸🩸

Knix model wearing Ultra Leakproof Zones+ Bikini underwear in Dark Teal display: full

Our Zones+ Ultra absorbent period underwear are not messing around when it comes to leak protection. These heavy-duty styles leave period and bladder leaks shaking in their boots. And for good reason—this is our most absorbent assortment of period underwear to date, featuring extended coverage zones for targeted protection where you need it most. 

Absorbency: Absorbs 13 to 17 tsps of menstrual fluid, sweat, and urine—which is about the equivalent of 7-9 super tampons.

Styles: Ultra Leakproof Zones+ Bikini and High Rise.

Best for: Wearing solo on your heaviest period days (and nights), as well as light bladder leaks during postpartum, menopause, and life’s other phases. 

For the full scoop on updated absorbency levels and product names, check out this comprehensive guide