Find Your Fit

If it’s your first time trying out a menstrual cup or period underwear, we understand that finding the right size of reusables product might be tricky. Our size guides will help you to find the right fit for you.

This can be used as a starting point. We hope it helps!


The TOM Organic menstrual cup comes in two sizes: Size 1 and Size 2.

SIZE 1 Menstrual Cup

This one is recommended for users aged 30 years and under, and mostly for those who have not given birth. Lighter to medium flow. Because our Size 1 cup is slightly shorter than Size 2, it can be better for those with a lower cervix.

If after reading through this guide you’re still unsure which cup is for you, we’d recommend you try Size 1 first.

The Size 1 TOM Organic menstrual cup holds an equivalent of 2 Regular Tampons.

The diameter of the Size 1 cup is 41.25mm and the overall height including the stem is 64mm (44mm excluding stem). It holds 22ml.

SIZE 2 Menstrual Cup

This one is best if you are over 30, or if you have given birth (note: it’s not only the measure of how you gave birth, the pressure of carrying a baby to term and the hormones can weaken your pelvic floor, regardless of how your baby was delivered). A heavier flow is best suited to a Size 2. Because our Size 2 cup is slightly longer than Size 1, it can be better for those with a higher cervix.

The Size 2 TOM Organic menstrual cup holds an equivalent of 3 Regular or 2 Super Tampons.

The diameter of the Size 2 cup is 45.8mm and the overall height including the stem is 70mm (50mm excluding stem). It holds 30ml.


Until you get the hang of it, we recommend wearing a pad or liner for extra protection and peace of mind.

Wear your menstrual cup (either size) for up to 8 hours.

We don’t recommend selecting your cup size based only on flow.

The cup size can be linked to your pelvic floor strength which holds your cup in place, but it’s not only related to how many Pilates classes you’ve done, your pelvic floor can weaken for lots of reasons including pregnancy, childbirth and simply from the change in hormone levels as we get older.

You may find that once you are well practiced in using a cup that either size fits comfortably.

For help in finding and measuring your cervix, watch the Put A Cup In It video.



The TOM Organic Period Brief comes in eight sizes, ranging from 2XS, XS, S, M, L, XL, 2XL, and 3XL to cover all size preferences.

Our period brief is a mid-rise style which sits a couple of centimetres below your belly button – giving you the coverage and security you need when you have your period. Because our period brief is designed to prevent leakage, you may find they have a slightly “snug” fit compared to regular underwear – but our soft elastic will keep you both comfy and dry.

Based on feedback, we recommend sizing up to ensure the leg holes of the brief aren’t too tight (e.g. if you generally wear a size 12, we recommend purchasing a size 14).

Use our size chart for help in finding the right size for your period undies. Note that the hip is measured 20cm below the waist (i.e. around the largest part of your bottom). The waist is measured around the base of your belly button.

If you’re measuring between two sizes, we recommend choosing the larger size (e.g. if your waist is measuring for a size L, and your hips a size XL, purchase the XL)

While you’re getting used to your new period undies, we recommend wearing them with either a tampon or a cup on heavier days.