Fertility guide · 4 min read
How to Calculate Your Fertile Window
Your fertile window is the span of days in a menstrual cycle when conception is more likely. Most simple estimates include the five days before ovulation and ovulation day.
Why the Window Starts Before Ovulation
The fertile window starts before ovulation because sperm may survive for several days in the reproductive tract. This means timing before ovulation can still matter.
Basic Formula
Estimated ovulation = last period start + (cycle length - luteal phase length)
Fertile window = estimated ovulation - 5 days through estimated ovulation day
What Can Change the Estimate
Cycle length, stress, illness, travel, breastfeeding, medication, and underlying health conditions can all shift ovulation timing.
Helpful Calculators
Medical Disclaimer
This article is for educational use only and is not medical advice, diagnosis, contraception guidance, or a substitute for a qualified healthcare professional.