The Boxer Brief
The Boxer Brief
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A comfy, mid to high-rise boxer brief made from super soft recycled nylon. Our machine-washable boxer brief period underwear is engineered for regular or light flow days, ideal as a standalone solution or reliable backup for heavy flow days.
(psst.. we've made some really cool updates to the boxer brief like: an extended gusset, a pad shaped gusset to allow more absorbency and comfort, and a softer waistband)
Product Details + Fit
Product Details + Fit
This style was made to stretch. Recycled nylon and a forgiving waistband make these perfect for people that experience bloating or heavy cramping–or that just want a lil' extra comfort on their period. They fit true to size, so we recommend ordering your usual size (if you're in between sizes, size up!)
Fabric + Care
Fabric + Care
- Shell: 88% Recycled Nylon, 12% Spandex
- Lining: 100% Cotton
- Gusset: 75% Bamboo, 25% Polyester
monthly period underwear are machine washable. Wash on cold with like colors. Hang to dry. It's that simple!
Impact
Impact
Switching to period underwear helps divert 4 tampons/pads from landfills every day you choose to use them! (not to mention they save you $ in the long term.) Good for you + good for the planet.
Design
Design
We talked to 250+ people with periods before designing our underwear. These folks had heavy flows, light flows, endo, PCOS, gender dysphoria, cramping, and everything in between. Based on these conversations and surveys, here's what we did:
- Made an ultra stretchy waistband so you don't feel restricted while bloating
- Full length boxer to allow for gender inclusion
- Floating gusset so you can wrap a pad inside the underwear in case of emergency or preference
- Ultra thin pad, so they feel just like your favorite pair of underwear
Trust us, we got your back when it comes to periods. All day comfort informed by real people with real periods. ☁️
FAQ's
FAQ's
Still need some more info on our underwear? Check out our FAQs page or shoot as an email at hi@shopmonthly.co.

Size Chart
Skip the guesswork—grab your hip measurement for the just-right fit! It’s the easiest way to find your perfect size, made just for you.
Here's how to measure:
- Stand relaxed with your feet together
- Wrap a soft measuring tape around the widest part of your lower hip section
- Match your measurement number to our size in the chart below
| Numeric | Waist (in) | Hips (in) | |
| xxs | 00 | 23.5 - 24.5 | 32.5 - 34 |
| xs | 0-2 | 25 - 26.5 | 34.5 - 36.5 |
| s | 4-6 | 27 - 29 | 37 - 39.5 |
| m | 8-10 | 29.5 - 31.5 | 40 - 42 |
| l | 12-14 | 32 - 35.5 | 42.5 - 44.5 |
| xl | 16-18 | 36 - 39.5 | 45 - 48.5 |
| 2x | 20-22W | 40.5 - 44 | 49 - 52.5 |
| 3x | 24-26W | 45 - 48.5 | 53 - 56.5 |
| 4x | 28-30W | 49.5 - 53 | 57 - 60.5 |
Planet-friendly
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ultra comfy
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low waste
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Gender-inclusive
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It's the absorbency for me
Our multi-layered gusset features a cotton top, two layers of absorbing bamboo blend fabric, and a breathable leakproof backing.
Our features
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Odor-resistant
Designed to keep you fresh with a cotton layer and bamboo blend for natural odor control
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Leak-proof
Our 4-layer gusset is ultra thin, but designed to absorb your flow and prevent leakage
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Absorbent
Our boxer brief holds about 25 ml of flow, which is equal to 1 menstrual cup, 3 super tampons, or 5 pads.
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Super stretchy
Ultra stretchy waistband and fabric that adapts to your body, offering a flexible fit that moves with you
Don't just take our word for it
This is my first time trying period underwear and I actually am obsessed, this changed the game!
-Rebe
These are so comfortable, I wear these even when I'm not on my period!
-Olivia
I've had my monthlies for about a year now, and I absolutely love them!
-Delilah
Wearing comfortable, cute, period undies helps you feel better
-Ada
I thought that menstrual underwear was the best it was going to get... until I tried monthly
-Peaches
monthly underwear helps me feel more confident in my body
-Aeja
Our customers are raving
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Our customers are raving
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Our customers are raving
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Real reviews from real people
- RSRachel S.Verified BuyerI recommend this productAge (optional) 31-42Products You Use for Period Management Period UnderwearFlow Level ModerateWhy did you switch to monthly? Comfortable, Sustainable/Reusable, Easier to UseRated 5 out of 5 stars3 days agoI own 6 now
This is the first period product I can truly say that I love. So comfortable, cute looking, and dependable.
Was this helpful? - SCSarah C. K.Verified BuyerI recommend this productAge (optional) 31-42Products You Use for Period Management Period Cup, Period Underwear, Pads, TamponsFlow Level ModerateWhy did you switch to monthly? Comfortable, Sustainable/Reusable, AffordableRated 5 out of 5 stars1 week agoSo comfortable!
Love these more than any other brand I've tried <3
Was this helpful? - SESha'rose E.Verified BuyerI recommend this productAge (optional) 31-42Products You Use for Period Management Pads, Tampons, Period UnderwearFlow Level ModerateWhy did you switch to monthly? Comfortable, Sustainable/Reusable, Affordable, Easier to Use, ConvenientRated 5 out of 5 stars1 week agoSo comfortable!
Always happy with my orders. These underwear are so soft. I feel secure when wearing them.
Was this helpful? - EEricaI recommend this productRated 5 out of 5 stars1 week ago5 Stars
Love my monthly boxers!! So soft and comfy! I got the matcha checkered ones!
Was this helpful? - AAI recommend this productRated 5 out of 5 stars1 week ago5 Stars
Comfy and functional!
Was this helpful?