Periods normally arrive once a month (every 28-30 days), but for many women it isn’t an exact science – predicting the precise date and length of your next period is sometimes tricky. That's where period calculators come in.


When did your last period start?

The date when you began your last period and you had continued bleeding (rather than just spotting)
Mon 01 Jan

How long does your period usually last?

Take a rough average of how long it's lasted over the last three months
5 Days
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The time between the beginning of one period and the start of the next – take a rough average
21 Days
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    The days before your period when PMS may rear its ugly head – learn how you can ease the symptoms
    When your cycle kicks into action and bleeding starts with your womb lining being shed
    Your bleeding should have stopped by this point, but you may still have a very light flow
    It's at this point when one of your ovaries releases an egg and you may have increased discharge

The results from our period tracker may not be 100% accurate and that’s because every body and every cycle is different.


So how does your cycle kick off? Well, it’s measured from the start of your period when you have regular bleeding (although you may notice some spotting before that). You might then be wondering where that blood has come from (and why there seems to be so much of it)?!

Your period happens because the womb lining is being shed; menstrual blood will come through your cervix and then your vaginal opening. This bleeding will usually happen for three to five days, and while you may think you’re losing pints of the stuff, the typical amount of blood in your menstrual flow is 30-40ml. For more info, look at our article on how much bleeding is normal.

After your period finishes, your body will begin prepping for ovulation again with your uterus lining (the endometrial lining) thickening to get ready for a fertilised egg. One of your ovaries will then release an egg which will come through one of your fallopian tubes down towards the womb. If it has met a sperm on its travels, then the egg will be fertilised and you can become pregnant. If that egg isn’t fertilised then the womb lining isn’t needed – it’s shed, and the whole process will begin again.

The average cycle is 28 days, but don’t worry if yours isn’t – it could be anything between 21 and 35 days, and it’s normal for this to vary a bit as well. Plenty of women have cycles that are slightly different in length from month to month. It’s likely that you’ll have a slightly longer cycle to begin with, but it will often become shorter as you get older.

If you’d like to know more about the different phases, then check out our article covering the ins and outs of the menstrual cycle.


It can be super handy to have a pretty firm idea of when your period will be coming your way. Your period should never stop you living your life, but if you’re worried about that big event or holiday then our tracker can help you plan ahead. You might even find that your cycle is more regular than you realise!

Doctors also use periods as an important indicator of a woman’s overall health and changes to it can be a symptom of some pretty key health issues. What’s important is to understand what is normal for you, so that you recognise when there are changes before discussing them with your GP.

And if you’re looking to have a baby? Well, our tool can give you a good estimate as to when you will be fertile so you have the best chance of getting pregnant.


Going through a busy spell at work or does it seem like you’re arguing with your family 24/7? Stress can be a key factor. Or are you pumping far too much iron at the gym? Excessive exercise can be another cause of an irregular period.

Weight loss (or gain), malnutrition, hormone imbalances, contraceptives, menopause and pregnancy can also trigger an irregular period. It’s important to realise that the occasional irregular period does happen (especially when you’re younger), but if you’ve had them for more than three months then you should see your doctor.

Get more info on irregular or missed periods here.


It’s worth noting that while period trackers can be helpful in many ways, they are never 100% accurate and therefore should only be used for guidance.

Because the human body is often unpredictable and everyone’s cycle is unique, a period tracker can never tell you with 100% certainty which days you don’t have to worry about getting pregnant, for example, or which days you definitely won’t be bleeding.

All in all though, period trackers are great tools to help you get to know your body and yourself better — bringing greater peace of mind and opening up an extra level of comfort. So if you're curious about what it can do, try out ours for yourself.

And to help you get the most accurate results from our tracker, use a diary or note in your phone to mark when your period starts and finishes for a few months, plus any other info you want to keep note of like details of your flow.

Personal data provided by users in the period tracker is not stored by Essity and is deleted when exiting the page.

Learn all you need to know

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