Hello and welcome to the Sustainable Cycle Blog!
Today I am talking about how to choose the right menstrual cup size — without the stress. Period care shouldn’t be another complicated decision in an already busy day. While I’m all for keeping things simple, finding a menstrual cup that feels comfortable, secure, and leak-free does mean considering a few important factors. In this post, I’ll break them down in an easy, practical way to help you feel confident in choosing the right fit for your body.
Before we dive in, a quick disclaimer: I am not a medical professional. While I do hold a degree in Biomedical Science, I have not practised medicine and do not hold a medical licence. The information in this post is based on researched sources.
Your flow and estimating capacity without the guesswork
If you’ve never used a menstrual cup before, it can feel impossible to know how many millilitres (ml) of menstrual fluid you lose per cycle — especially since most cups are sized by capacity. The good news? You can make a pretty accurate estimate based on what you already use.
If you currently use tampons or pads, think about:
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How many you use per day
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How quickly they fill
According to the Centre for Menstrual Cycle and Ovulation Research (CemCOR), a regular tampon holds approximately 5 ml of fluid.
So, for example:
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If you use around 5–6 tampons per day, that’s roughly 25–30 ml of fluid. In this case, the larger Pachamama menstrual cup (35 ml) may be better suited and could comfortably last 10–12 hours.
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If you use fewer tampons per day, the smaller Pachamama cup (30 ml) may be a better fit.
This method isn’t perfect, but it’s a helpful starting point if you’re new to cups.
Does shape matter?
Menstrual cups come in many different shapes, which can make choosing one feel tricky.
Pachamama currently offers a bell-shaped cup, which is the most common and widely used design. Bell-shaped cups rely on gentle suction to stay in place and work well for many people.
Other designs you may come across include:
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Menstrual discs, which sit higher in the vaginal canal and don’t rely on suction. Some people find these more comfortable, especially if they’re sensitive to the suction feeling.
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Curved cups, which are designed to better accommodate a tilted cervix.
Comfort is highly individual, so if one design doesn’t work for you, it doesn’t mean menstrual cups aren’t for you, just that a different shape may suit you better.
What your cup is made of matters!
There are two main materials used to make menstrual cups:
Medical-Grade Silicone
The Pachamama menstrual cup is made from 100% medical-grade silicone, the gold standard for menstrual cups. Silicone cups tend to be:
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More flexible and malleable
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Easier to insert and remove
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Able to retain their shape once removed
They can be slightly more expensive, but many people find the comfort and longevity worth it.
Thermoplastic Elastomer (TPE)
TPE cups are often more cost-effective but tend to be firmer than silicone cups. While they can work well for some users, others may find them less comfortable.
Age, childbirth, and pelvic floor changes
Age and whether you’ve given birth can play a significant role in cup sizing.
If you have given birth vaginally, pelvic floor muscles may be weaker and the vaginal canal may have changed. In these cases, a larger menstrual cup is often recommended, as it can sit more securely and reduce the risk of leaks.
Similarly, if you are over 30–40 years old, natural changes in pelvic floor strength can occur over time. A larger cup may provide better support and comfort.
On the other hand, younger people, particularly teens or those under 30 who have not given birth, may find a smaller cup more comfortable and easier to insert and wear.
Final Thoughts
Choosing the right menstrual cup is about understanding your body, not fitting into a one-size-fits-all rule. Flow, design, material, age, and life experience all play a role, and it’s okay if it takes a little trial and error.
The goal is simple: comfort, confidence, and fewer things to think about during your period.
Liz x