The Boxer Brief
The Boxer Brief
*please allow up to 2 weeks for shipping*
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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
- VVapeI recommend this productRated 5 out of 5 stars4 days ago5 Stars
Hiya! I've fallen for the matcha checker propaganda and they are insanely comfy for me, as well as stylish 🥺❤️ when they came in I had a severe dislike for the waistband (it was comfy, just really tight and uncomfortable where it rested near my navel and sometimes a little higher)
But stretching the waistband forwards a bit did the trick and gave me enough room for my bloated tumtum. It's insanely comfy (in case you didn't hear me say that part yet) and is absolutely body tea when it's tried on
Already ordered another pair and the heavy version of this for the extra security. All in all, this is a great boxer brief I happened to come across randomly on my Instagram page, and I do not regret giving these a try! ❤️
Was this helpful? - CJCourtney J.Verified BuyerI recommend this productAge (optional) 31-42Products You Use for Period Management DiscFlow Level ModerateWhy did you switch to monthly? OtherRated 5 out of 5 stars1 week agoNever thought I would I love period underwear
Editing my review because below it ask me 'why' I switched to period underwear....well it was my husband actually.
He went to college with the owner of Monthly. He simply wanted to support a small female owned business and bought me a pair to try. I was willing to give them a shot but wasn't very optimistic. I had tried period underwear before and never liked them.
After the first use of monthly underwear I immediately bought a second pair. The fabric is so so SO soft. I love these to sleep in and feel like my heavy days are so much more comfortable. I can't believe how much I love this product.
The first pair fit true to size and comfortably, but for my second pair I did size up one size. I wanted my second pair to have extra room for my most bloated uncomfy days. I like having both size options for when I want more room in the waistband.
I will be buying more pairs and im glad my husband introduced me to something that makes my period more comfortable.
Was this helpful? - ASalexandra s.Verified BuyerI recommend this productAge (optional) 25-30Products You Use for Period Management Reusable Pads, Period Cup, Period UnderwearFlow Level ModerateWhy did you switch to monthly? Sustainable/Reusable, Gender Affirming, ComfortableRated 5 out of 5 stars1 month agosuper comfy and sensory friendly!!!!
i love these boxers so much. they’re super comfortable even on days when i’m bloated! the fabric is lightweight and super stretchy. my stomach is sensitive and i really don’t like tight things and even the waistband on these is really comfy. for reference im a 32” waist and bought a size large. the pad part is lightweight and doesn’t feel bulky, which can be an issue for me. i was a little nervous at first because the absorbent part is narrower than period undies i’ve had before, but was pleasantly surprised and it stays where it’s supposed to be. i typically wear these while wearing a menstrual cup and haven’t tried them solo on my heaviest days yet. i also love the colorways, that everything comes in curbside recyclable packaging, and that the descriptions and marketing are gender neutral!!!! i bought one pair to try them out first and then quickly ordered 3 more :)
Was this helpful? - EEricaI recommend this productRated 5 out of 5 stars2 months ago5 Stars
The MOST comfortable period underwear ever!!! I love lounging in them around my house!! I love the new stretchy waistband!!! I need more!! Thank you for making the “pay what you can sale” I’m very lucky to own these <3
Was this helpful? - DDracoI recommend this productRated 5 out of 5 stars2 months ago5 Stars
i was nervous to use them as they’re my first pair of period underwear but they do feel incredibly comfortable and are able to keep up with me!! would buy again
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