How to Choose the Right Menstrual Cup Size and Firmness

Quick answer

Start with your age, birth history, pelvic floor strength, and flow volume. If you've never given birth vaginally, choose a small or medium cup with medium firmness. If you have a heavy flow or a stronger pelvic floor, opt for a larger, firmer cup. When in doubt, pick a softer cup for comfort—it's easier to insert and remove.

Choosing the right menstrual cup is about more than picking a random size. The right fit depends on your anatomy, flow, and comfort. A cup that's too firm can press on your bladder or cause cramps, while one that's too soft may leak or be hard to remove. This guide gives you clear rules to make the decision easier.

We'll walk through the key factors—size, firmness, and shape—and show you how to test your fit. By the end, you'll know exactly what to look for and how to adjust if your first cup isn't perfect.

Size: It's Not Just About Flow

Menstrual cup size usually correlates with flow volume, but anatomy matters just as much. Most brands offer small and large sizes. Small cups (about 35-40 ml) suit light to medium flow, younger users, or those who haven't given birth vaginally. Large cups (40-50 ml) are for heavy flow, older users, or those who've had a vaginal birth.

Your cervix height also plays a role. If your cervix sits low, a shorter cup may be more comfortable. If it's high, a longer cup is easier to reach. You can feel your cervix with a clean finger during your period—it feels like a firm, round nub. This helps you estimate the cup length you need.

• If you're between sizes, start with the smaller one—it's easier to insert and less likely to put pressure on your bladder.

Firmness: The Trade-off Between Comfort and Security

Firmness affects both comfort and how well the cup seals. A firmer cup pops open easily and creates a strong seal, which is great for heavy flow or active days. But it can press on your bladder or bowel, causing discomfort or even cramps. A softer cup is more comfortable and molds to your body, but it may be harder to open and can leak if your pelvic floor is strong.

Your pelvic floor strength is a key factor. If you do regular Kegels or have a strong pelvic floor, a firmer cup may be needed to stay in place. If you have a weaker pelvic floor (common after childbirth), a softer cup may be more comfortable and still seal well.

• Start with a medium-firm cup if you're unsure—it balances comfort and security.

Shape and Rim: Small Details That Matter

The shape of the cup affects how it sits and how it feels. Bell-shaped cups are common and suit most anatomies. V-shaped cups are narrower and may be more comfortable for those with a sensitive bladder. The rim—the top edge—can be round and firm or have a softer, more flexible edge. A softer rim is easier to insert but may not create as strong a seal.

The stem length also matters. If the stem pokes out or irritates, you can trim it, but don't cut it too short or you'll have trouble removing the cup. Always leave a little length to grip.

• If you feel the cup pressing on your bladder, try a softer or shorter cup.

Decision Rules for Cup Size and Firmness

• If you've never given birth vaginally: Choose a small or medium cup. Your pelvic floor is likely tighter, so a medium-firm cup will seal well without being too stiff. Start with a small, medium-firm cup.
• If you've had a vaginal birth: Your pelvic floor may be weaker, so a larger cup with a softer rim may be more comfortable and still seal effectively. Consider a large, soft cup.
• If you have a heavy flow: Opt for a larger capacity cup. A firmer cup will stay in place better, but if you're sensitive, try a softer one with a higher capacity. Choose a large cup with medium-firm firmness.
• If you have a low cervix: Pick a shorter cup to avoid discomfort. A softer cup will also conform to your shape better. Look for a short, soft cup.

Related Products to Support Your Cycle

• Red Jasper Yoni Eggs: Using a Red Jasper yoni egg is an incredible way to draw you back to your own inner being as you care for and strengthen the most sacred part of your body. Strengthening your pelvic floor with yoni eggs can improve your menstrual cup seal and reduce leaks, making your cup experience more comfortable and secure.
• Guided Womb Meditation: This guided meditation will take you on a journey of honoring your most sacred space, your womb. Through breath, sound, affirmations and meditation you're able to connect on a deeper level igniting your feminine spirit. Connecting with your body through meditation can help you become more aware of your pelvic floor and cervix, making it easier to choose and insert the right cup.

Fit Guidance: What Works Best

Best for

• Beginners who want an easy, comfortable fit—a small or medium cup with medium firmness.
• Active users who need a secure seal during exercise—a firmer cup with a higher capacity.

Not for

• Those with a very sensitive bladder or a low cervix—a firm, long cup may cause discomfort or pain.
• Those with a very heavy flow who need maximum capacity—a small or soft cup may leak.

Choosing the right menstrual cup is a personal journey. Start with the rules above, but don't be afraid to experiment. If your first cup isn't perfect, try a different size or firmness. Your comfort and confidence will come with practice. And remember, tools like yoni eggs and womb meditation can deepen your body awareness, making the whole process more intuitive.