The highlights:

  • A menstrual disc sits in the vaginal fornix (a.k.a. the widest part of your vagina and the base of your cervix) whereas a menstrual cup is placed in the vaginal canal
  • A menstrual cup has a bell-shaped design; a menstrual disc has a flat-fit design that looks more like a shallow bowl or dish
  • Both menstrual discs and menstrual cups collect your period blood, rather than absorbing it 
  • Menstrual discs are held in place thanks to your pubic bone; menstrual cups are kept in place with suction
  • Cups are always reusable, whereas menstrual discs are either reusable or disposable (single-use)

The full read:

Calling a menstrual disc and a menstrual cup the same product would be like equating eyeglasses to contact lenses. Sure, both of them do the same thing (correct your vision), but they’re totally different products that are used in different ways. 

Both menstrual cups and discs are period products designed to collect menstrual fluid, but their designs and ways of working in the body are quite different. Read on to learn the key differences between a menstrual disc and a menstrual cup—including how they are used, the materials they’re made from, positioning in your body, and what activities you can do with each period product.

Menstrual disc vs. menstrual cup placement

A menstrual disc sits in the vaginal fornix, which is at the base of your cervix. This area is the widest part of your vaginal canal, which is why the disc looks wider than a cup. Most of us have always thought of the vagina as shaped like a tube that stays the same width from front to back, but this isn’t actually the case!

Menstrual cups, on the other hand, sit in the narrower, lower portion of your vagina—the vaginal canal. There are more nerve endings in the vaginal canal than there are in the vaginal fornix, which is why some users find menstrual discs to be more comfortable than cups.

If you’re familiar with tampons, both tampons and menstrual cups sit in approximately the same position in the vagina. With a menstrual cup, you’ll have a bit more control over exactly where (or how far up) the product is placed than you would with an applicator tampon. This is because you use your fingers to manually insert and place the menstrual cup in the right position for your body. 

Flex Disc inserted in the vaginal fornix (left); Flex Cup inserted in the vaginal canal (right)

How each product works: Different mechanisms

A menstrual disc stays in place because your anatomy (including the muscular vaginal walls and the pubic bone) works together to keep it “propped up” within your vaginal fornix. The fornix is the widest part of your vagina and is located at the end of the vaginal canal, surrounding your cervix. 

There are two sides of the fornix, called the posterior (rear) and anterior (front) fornices.

Your pubic bone works like a shelf: You insert the disc at an angle—think down and back as far as it will go—so that it covers your cervix. When you’ve pushed the disc as far back as it will go, you then use your finger to tuck the front-facing rim behind your pubic bone with an upwards motion.

When properly inserted, your menstrual disc’s back rim (the side that entered your body first) rests in the posterior fornix, while the front rim sits up behind the pubic bone.

When it’s time to remove your menstrual disc, you just use a clean finger to hook the front rim of the disc, “untucking” it from behind the pubic bone, and carefully pull it out. 

In contrast, a menstrual cup uses suction to stay in place (plus a little help from the vaginal muscles). When it “pops” open in the vaginal canal, the edges of the cup create a seal against the vaginal walls, preventing leaks and keeping the cup in place. Therefore, when you want to remove a menstrual cup, you have to break the suction seal by pinching the base of the cup. 

With Flex Cup, breaking the seal is as easy as pulling down on the patented pull-tab—we designed our cup to work similarly to a tampon for greater ease of use and a less messy removal. 

Menstrual cup insertion vs. menstrual disc insertion 

To insert a menstrual disc, you pinch it in half, insert it into the vagina with two clean fingers, and then use a single finger to push it down and back into the vaginal fornix. Once it’s as far back as possible, you use that same finger to position the front-facing side of the rim up and back, tucking it behind your pubic bone (as described above).

Pinch Flex Disc to insert (left); fold Flex Cup to insert (right)

Inserting a menstrual cup requires folding (rather than pinching) as the first step. There are several folding methods you can try, including the punch down-fold, the C-fold, and the 7-fold. 

Once you’ve mastered your fold, insert the folded cup into your vaginal canal with clean fingers. As soon as it’s in a comfortable position far enough up your vaginal canal, check to make sure it’s opened up all the way. Some users like to rotate their cup slightly to help it create a seal with the vaginal walls. You may also run your finger around the rim to ensure it’s completely unfolded. 

Watch the difference in cup versus disc insertion in these two videos:

How to Insert Flex Disc (YouTube)
How to Insert Flex Cup (YouTube)

Menstrual discs are disposable or reusable; menstrual cups are only reusable

While all menstrual cups are reusable, menstrual discs are available in either reusable or disposable versions.

If you want to create as little waste as possible during your period, a reusable menstrual disc—like Flex Reusable Disc—or a menstrual cup is your best choice. They’re made with medical-grade silicone and hold up for years (so long as you take good care of them). 

Menstrual cups and reusable period discs must be emptied and washed before reinsertion; they should also be boiled every month at the end of your period to completely disinfect them. For daily washes, we recommend using a mild soap that won’t damage the silicone. Our favorite? Flex Foaming Cup Wash, designed specifically for cleansing silicone menstrual cups and discs.

The original Flex Disc is disposable (left); Flex Cup is reusable (right).
Check out Flex Reusable Disc for a more sustainable period disc option.

Disposable menstrual discs, like the original Flex Disc, are a more convenient and travel-friendly option for some menstruators. Since they are single-use, like a tampon, you don’t have to worry about cleaning or rinsing when you need to change your disc in a public restroom. Just dispose of your used disc and insert a new one.

While single-use products aren’t as sustainable as reusable products, disposable menstrual discs like Flex Disc still create 60% less waste than traditional period products (like applicator tampons and pads). This is because you can wear your disc for up to 12 hours, meaning a single disc will last an entire day—much longer than a tampon or pad.

Longer wear = fewer products used each period.

Sex on your period: Can you have sex with a menstrual disc?

A menstrual disc doesn’t block the vaginal canal, so it is possible to have mess-free, penetrative period sex while wearing one. It’s unlikely that either you or your partner will feel the disc, thanks to its positioning in the vaginal fornix, which is wider than the vaginal canal (and located at the very “back” of your vagina, surrounding your cervix). 

The same is not true for a menstrual cup: Because a cup sits inside the vaginal canal, it blocks anything else from entering. Therefore, you’ll need to remove your menstrual cup before having penetrative sex. 

Non-penetrative sex is still on the table with either product!

Flex Disc can be used during sex (left); Flex Cup cannot (right)

Cups & discs: Different materials

Disposable menstrual discs are made from body-safe polymers—including Flex Disc, which is made from a medical-grade polymer. Medical-grade polymers are FDA-regulated materials used in many types of medical devices, including surgical tools. 

Menstrual cups and reusable menstrual discs are usually made from medical-grade silicone, although some brands use different materials, such as rubber or latex. Both Flex Cup and Flex Reusable Disc are made with 100% medical-grade silicone.

The medical-grade silicone and medical-grade polymers used in Flex products are biologically inert, which means they do not interact or cause a reaction when introduced to human tissue (unlike a material like cotton, which is porous). Both cups and discs made with these materials are completely body-safe and, because they’re biologically inert, they do not host toxic bacteria or alter your vaginal pH.

All Flex period products (disposable and reusable) are FDA-registered, hypoallergenic, and are not made with BPAs, PFAs, phthalates, or natural rubber latex.

Have questions about Flex Cup, Flex Reusable Disc, or Flex Disc? Need help deciding which product is best for you? Our Flexperts are always available to chat: Just send us a message or email us at hello@flexfits.com