This topic deserves a deep-dive. It's not just whether or not you're over 30 or if you've given birth that determines your size. So here's everything you need to know about choosing the best size for you :)
LENGTH IS KEY
When we're talking about size, it's important to state that the most important dimension of a cup is LENGTH, not diameter. Basically, a cup should sit completely inside your vagina (apart from the stem, which can poke out).
So how do you determine if a cup is too long for you? It's all about the height of your cervix. Our cervix connects our vagina to our uterus, and, is totally unique to each person.
HOW TO MEASURE YOUR CERVIX HEIGHT
It may sound intimidating, but measuring your cervix is super quick & easy. You can also do it at home. Whilst we always advocate seeking professional advice for any medical issue, this is really not worth the trip to your gyno. Quite on the contrary, we should all feel comfortable enough with our bodies to explore it (safely!) in the comfort of our own homes.
Since periods often affect our bodies physically, we highly suggest doing this around the time you're menstruating. As always, the first rule is to carefully wash your hands. Then, take your finger and slide it into your vagina (as if you were inserting a tampon). Keep going until you feel something a bit firmer, similar to the touch to the tip of your nose. Good job: that's your cervix!
- If you can only get one joint of your finger in before feeling the cervix, then you probably have a low sitting cervix.
- If you can get two joints, then you probably have an average sitting cervix.
- If you can get the entire length of your fingers, then you probably have a high sitting cervix.
Generally, a bigger cup size is better for a higher cervix & a small is better for a lower cervix.
If you want to be really precise, with the tip of your finger still touching your cervix, place your thumb along your finger to mark all the length that fits inside. Keep the thumb in place as you remove your finger, and measure the distance to the tip of your finger with a ruler. Then you can easily compare that to the length of different cups!
AGE & PREGNANCY
If we go back to our initial diagram, you'll see that a bigger size is recommended for those over 30 or who've given birth. While this is a good general tip, it's definitely not definitive.
You may be in your 30s and find that a size large is uncomfortable, likewise, if you're younger you may also find that a small isn't big enough. Our bodies are ALL different.
Cups have to create suction with our vaginal walls, so it's important the cup sits pretty snugly inside you. Generally speaking, giving birth and ageing can both affect the size of our vaginal canal. In birth, this is because muscles tend to loosen in preparation for labor. Because of this, it's also important to note that women who've given birth through C-section may sometimes prefer a larger size too.
In general, it's good to remember that our vagina can easily expand but will struggle to constantly hold something in place. So if you're really undecided about which size to choose, sizing up may be more comfortable.
Unlike pads or tampons, your flow doesn't really need to be taken into consideration when choosing a cup. Cups have a much larger capacity: while tampons & pads should be changed every 4-6 hours, cups can usually last you 12 hours (although some women prefer rinsing them out more often).