How to measure your cycle

Period cycle

What is “Day One” of my cycle and why is it important to know when it is??

The first day of your period is easy to recognize – even if it is very light, so this is the day doctors calls  day one of your cycle.

By keeping a note of this, you can begin to keep a record of the length of your cycle, as although most women’s will be around 28 days long, some will vary by as much as three or four days either way or more – this is completely normal.

So, assuming your cycle is 28 days, you count from Day One and then when you start your next period, you begin again at Day One.

When will I ovulate (release an egg)?

You are at your most fertile just before and just after you ovulate. You can work out when you will be most fertile by deducting 14 and then 16 days from the date of your next period – these couple of days is when you’re most likely to get pregnant. This is approximate and may not be the same for every woman.

You can visit our ovulation calendar and start to plot your periods. Try this for a couple of months so you can see what your own personal pattern is and then work out when you are most likely to ovulate. You’ll know that’s the best time to try for a baby next month!

Note that these calculations may not be accurate if your ovulation cycle is less than 21 days long or more than 35 days, or if your menstrual cycle is irregular from month to month. Please consult your doctor for more detailed information on ovulation and the most fertile time for you if you are trying for a baby.



i came on very light after finishing my 21 days on the pill, on Tuesday June 26th for a few days then stopped. the Bounty OV calender said i will be ovulating between July 6th and 11th but i stated to bleed this morning, July 7th, and i having my normal period pains so i dont know how to determine the first day of my cycle.

still not pregnant

been trying for 6 months i already got 2 children boy and girl but i finding third time round harder i am 33!! and no promblem in my health or my husband any help out there? my period are not all way the same some are very 26 days and then they are 28 days how will i know my ovalation dates

what's wrong ?

I have been having unprotected sex with my partner for 3 years now since iv been 18 ,, still nothing , iv had test and they have all come back fine , my partner also has results come back fine ????

still not pregnant

me and my husband have been trying everything nothink works when i have my period i get upset ive already have children whats wrong with me

Doesnt seem to be happening.

Been trying for a baby now for about 7 months, Still nothing seems to be happening. Ive had a misscarage and an eptopic pregnancy, Could there be something wrong with me?

still not pregnant

been trying for about 6 mths all in all already have 2 daughters really finding it hard to get pregnant third time round is it my age im 34!! Never had this problem with the other 2 pregnancies??

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.