Ovulation & Fertility Calculator
Predict your most fertile days and ovulation date based on your cycle length.
Fill in your details, then check your personalized result and recommendations.
Formula
Ovulation ≈ next period − 14 days; fertile window = 5 days before to 1 day after
Worked example
28-day cycle → ovulation around day 14
What the ovulation calculator does
This tool predicts your likely ovulation date and the fertile window around it, the days each cycle when conception is most likely. It also estimates when your next period is due, which is useful whether you are trying to conceive or simply tracking your cycle.
How the calculation works
Ovulation typically occurs about 14 days before the start of your next period, regardless of cycle length. The calculator finds your next expected period from your cycle length and counts back 14 days. Because sperm can survive several days, the fertile window spans the five days before ovulation through one day after.
How to interpret your result
The fertile window is your best opportunity for conception. These dates are estimates based on an average cycle; actual ovulation can shift due to stress, illness, travel, or natural variation. Combining this prediction with ovulation predictor kits, basal body temperature tracking, and changes in cervical mucus gives a much clearer signal.
Health recommendations
If you are trying to conceive, aim for intercourse during the fertile window and maintain general healthy habits. If your cycles are very irregular or you have been trying for over a year (or six months if over 35), consult a healthcare professional. This tool offers general guidance and is not a contraceptive method.
FAQ
+When am I most fertile?
The five days before ovulation and the day of ovulation itself are the most fertile.
+How accurate is ovulation prediction?
It is an estimate; ovulation tests, basal temperature and cervical mucus improve accuracy.
+Can I ovulate on a different day each month?
Yes — stress, illness and cycle variation can shift ovulation timing.