Your cervix and menstrual cups

When you choose a menstrual cup, you’ll often hear people talk about their cervix being low, high or somewhere in between. It’s the question I get asked most in my emails. In this guide I explain what the cervix is, how to measure your cervix height with one finger, and how to use it to find your Goldilocks cup.

What is the cervix?

The cervix is a small but very important part of your anatomy: it’s the passage between your vagina and your uterus. It looks like a little doughnut of flesh about 3 cm across, and its firmness changes with your menstrual cycle, pregnancy and arousal. A tiny opening in the middle lets sperm swim in and menstrual fluid flow out, and during labour it can stretch to 10 cm.

You can see photos of real cervixes, and how they change through the cycle, at the Beautiful Cervix Project.

Why does your cervix height matter when choosing a menstrual cup?

Buying shoes that don’t fit is uncomfortable. Now imagine buying something for your vagina that doesn’t fit! A menstrual cup has to sit below your cervix to collect the flow, while being fully inside your vagina, stem included. If the cup is too long for you, it pokes out or presses on the cervix; if the cervix ends up beside the cup instead of above it, the flow goes right past it and you get leaks.

So find out your cervix height, check the length of the cup, and see how they measure up before you buy your menstrual cup. Your cervix isn’t the only factor: your flow, the tone of your pelvic floor and your childbirth history also play a part. Read my tips on how to choose a menstrual cup.

How do I measure my cervix height?

Measure it during your period, because that’s when your cervix usually sits lowest, and that’s when the cup has to fit.

1. Wash your hands and trim the nail of the finger you’ll use.
2. Get comfortable. Stand with one foot raised on the toilet or bath, squat, or sit on the toilet. Use the same position you’d use to insert a cup.
3. Relax. Take a few deep breaths and let your pelvic muscles soften. Tension makes it harder.
4. Insert your index or middle finger and slide it in gently, angled towards your lower back, until you touch something firmer than the vaginal walls. That’s your cervix. It feels a bit like the tip of your nose, round with a small dimple in the middle.
5. Note how far your finger went in, by looking at which knuckle is level with your vaginal opening.

What your measurement means

• Low cervix (44 mm or less): you reach it with your finger in up to the first knuckle.
• Medium cervix (45 to 55 mm): you reach it with your finger in up to the second knuckle.
• High cervix (over 55 mm): you reach it at the third knuckle, or you can’t reach it at all.

The knuckle method is only a rough guide, as every hand is different. For a precise measurement, mark your finger at the opening with your thumb and measure it against a ruler.

As a rule of thumb, choose a cup whose body is shorter than your cervix height, ideally by about 1 cm, since a cup sits just above the vaginal opening. If you have a low cervix, the stem will often need trimming.

Free visual tool

See which cup fits your cervix

Now that you know your cervix height, try our compare tool: pick any two menstrual cups, see them drawn to real scale next to a finger, and drag the slider to your cervix height. It tells you straight away whether each cup fits, is snug or is too long.

Try the compare tool →

How your cervix moves during your menstrual cycle

Your period isn’t the only thing your hormones change: your cervix moves throughout the month too. Around ovulation it usually sits higher and feels softer; around your period it drops lower and feels firmer. It can even change during your period itself, so it’s worth checking on different days to make sure your cup fits all the way through.

Here’s a general overview, based on a 28-day cycle:

1. Period (days 1 to 5): the cervix is usually at its lowest, firm and easy to reach.
2. After your period (days 6 to 13): as estrogen rises, the cervix slowly moves up and becomes softer.
3. Ovulation (around day 14): the cervix is usually at its highest, very soft (a bit like touching your lips) and slightly open.
4. Luteal phase (days 15 to 28): as progesterone rises, the cervix moves back down and becomes firmer and more closed.

These are general patterns and everyone is different: some people notice big changes, others hardly any. Tracking your cervix position can be part of fertility awareness, but on its own it isn’t a reliable method of contraception or for predicting fertility.

Does the position of your uterus matter?

Your uterus can sit in slightly different positions, and this changes the angle of your cervix. That matters for cups: if your cervix points more forwards or backwards, a cup can sit off-centre and leak. If that happens, angle the cup more towards your tailbone when you insert it, and check that your cervix sits inside the rim.

1. Anteverted uterus: the uterus tilts forwards, towards the bladder. This is the most common position.
2. Anteflexed uterus: the body of the uterus bends forwards over the cervix. Often found together with an anteverted uterus, and completely normal.
3. Retroverted uterus: the whole uterus tilts backwards, towards the spine. Around 1 in 4 or 5 women have this; it’s a normal variation, though it can sometimes come with period pain or discomfort during sex.
4. Retroflexed uterus: the body of the uterus bends backwards over the cervix. Also a normal variation.

Your uterus position can change over your lifetime, for example after pregnancy or childbirth. Most positions are simply variations of normal. If you have ongoing pain, talk to your doctor or gynaecologist.

Menstrual cups for a low cervix

With a low cervix (44 mm or less), look for a cup body of 44 mm or shorter, and plan to trim the stem.

• Me Luna Shorty: made for a low cervix, with cup bodies from just 35 mm (size S) to 44 mm (XL).

If your cervix is right on the border, around 45 to 46 mm, these short cups are also worth a look:

• Intimina Lily Cup One: a 45 mm body and a handy ring stem.
• Me Luna Classic size S: 45 mm, with a choice of stem, ball, ring or no stem.
• Lalicup size S: 46 mm, soft and easy to fold.

Menstrual cups for a high cervix

With a high cervix (over 55 mm), a longer cup, with a body over 55 mm, is easier to reach and less likely to slide up out of reach.

• Lalicup size XL: one of the longest cups, with a 62.5 mm body.
• Intimina Lily Cup: long and slim, 59 to 60 mm, designed for a high cervix.
• Yuuki size 2: 56 mm, available soft or classic.
• Me Luna Classic XL: 56 mm with a large capacity.

Frequently asked questions

What counts as a low cervix?

A cervix 44 mm or less from the vaginal opening is considered low: you can usually reach it with your finger in up to the first knuckle. Medium is 45 to 55 mm, and high is over 55 mm. Not sure which cup fits? Compare any two cups to scale against your cervix height.

Does my cervix height change during my period?

Yes. Your cervix is usually at its lowest during your period and can move a little from day to day, so measure it on more than one day of your period.

What if I can’t reach my cervix?

Then you most likely have a high cervix. Try again during your period, squatting, when it sits lowest. If you still can’t reach it, choose a longer cup.

Is a menstrual disc better for a low cervix?

Often, yes. A disc sits flat behind the pubic bone instead of in the vaginal canal, so its length doesn’t matter the way a cup’s does.