The fertility cycle starts on the first day of your period. Many women mistakenly believe that ovulation occurs 'mid-cycle'.
Only if a woman's cycle is a regular 28 days does she ovulate mid-cycle, around day 14. If her regular cycle is 25 days, then ovulation occurs around day 11 and a cycle of 35 days means ovulation occurs around day 21.
Zita West, author of Zita West's Guide To Getting Pregnant
Where next?- Get more help with our ovulation calculator
- Read our expert advice on having more sex
- Find out how to take the stress out of trying for a baby
- 11 things you need to know about ovulation
- Get tips to boost your love life on our Sex & relationships channel