Automatically calculate your ovulation day and fertile window based on your menstrual cycle to help you find the best time to conceive.
Please enter your menstrual information to view prediction results
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If you are unsure about the best time to conceive each month, this tool automatically calculates your ovulation day and the 5-day fertile window before and after it, based on the date of your last period and your cycle length. Ovulation is typically defined as occurring 14 days before your next period (the luteal phase) and is the critical day when the probability of the sperm fertilizing the egg is highest.
Is the ovulation calculator accurate?
It has an accuracy rate of about 85% for women with a regular 28-day cycle. The greater the cycle fluctuation, the larger the margin of error.
How can I improve the accuracy of ovulation prediction?
We recommend combining this tool with the basal body temperature (BBT) method. Your body temperature rises by 0.3-0.5°C after ovulation. Continuously measuring your BBT for 3 cycles can help establish your personal baseline curve, which works best when used alongside this tool.
Stress, medications, or endocrine disorders can cause your actual ovulation day to shift by 2-3 days from the predicted result. If you have been trying to conceive for over 6 months without success, we recommend consulting a doctor. This tool is not a substitute for professional medical diagnosis.
Typical Example: Entering 2023-05-01 (last period) and 28 (cycle length) will output 2023-05-15 (ovulation day) and 2023-05-10 to 05-19 (fertile window). It is recommended to have intercourse every other day during your fertile window. Since sperm can survive in the female reproductive tract for 2-3 days, this schedule maximizes your chances of conception.
