Fertile Window Calculator
Calculate your fertile window — the 6-day period (5 days before ovulation plus ovulation day) when conception is most likely.
How to Use the Fertile Window Calculator
Calculate your fertile window — the 6-day period (5 days before ovulation plus ovulation day) when conception is most likely. Enter your information in the form above and get instant results.
Medical Disclaimer: This tool is for informational purposes only. Always consult your healthcare provider for medical advice.
Frequently Asked Questions
What is the fertile window?
The fertile window is the 6 days ending on ovulation day. Sperm can survive up to 5 days, so intercourse before ovulation can lead to conception.
Which day in the fertile window is best?
The two days before ovulation and ovulation day itself have the highest conception probability — up to 30% per cycle.
How do I confirm ovulation?
Use LH ovulation predictor kits (OPKs), track basal body temperature (BBT), or monitor cervical mucus changes.