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.
The date when you began your last period and you had continued bleeding (rather than just spotting)
When did your last period start?
Take a rough average of how long it's lasted over the last three months
How long does your period usually last?
The time between the beginning of one period and the start of the next – take a rough average
How long is your cycle?
- peak ovulation
Pre-Period The days before your period when PMS may rear its ugly head – learn how you can ease the symptoms
Period When your cycle kicks into action and bleeding starts with your womb lining being shed
Post-Period Your bleeding should have stopped by this point, but you may still have a very light flow
Peak Ovulation 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.
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 alterations in your period.
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.