Fertility Window Calculator

Calculate your 6-day fertility window for the next 3 months. Based on your cycle length and LMP for accurate conception planning.

Please select your LMP date.

What Is the Fertility Window?

The fertility window is the period in each menstrual cycle during which sexual intercourse can result in pregnancy. It spans approximately 6 days: the 5 days before ovulation and the day of ovulation itself. This window exists because sperm can survive in the female reproductive tract for up to 5 days, while the egg survives only 12–24 hours after ovulation.

Maximising Your Chances of Conception

The two days immediately before ovulation and ovulation day itself carry the highest probability of conception. Having intercourse every 1–2 days throughout the fertile window gives the best chance of success. Daily intercourse during this period is not necessary and does not significantly improve outcomes compared to every-other-day timing.

When to Seek Medical Advice

If you have been trying to conceive for 12 months without success (6 months if over 35), speak with a fertility specialist. Common causes of difficulty conceiving include ovulatory disorders, polycystic ovary syndrome (PCOS), tubal blockages, and male factor infertility.

Frequently Asked Questions

How do I know if I’m in my fertile window?
Calendar tracking gives an estimate, but physical signs are more reliable: egg-white cervical mucus, a slight rise in basal body temperature after ovulation, or a positive result on an ovulation predictor kit (OPK).
Can stress affect my fertility window?
Yes. Significant physical or emotional stress can delay or suppress ovulation, effectively shifting the fertile window later in the cycle or preventing ovulation entirely for that cycle.
Is there a fertility window when breastfeeding?
Breastfeeding suppresses ovulation for many women (lactational amenorrhoea), but it is not a reliable contraceptive method — ovulation can return unpredictably, sometimes before the first post-partum period.
Medical Disclaimer: This calculator is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for health decisions.