Ovulation & Fertility Calculator
Calculate your ovulation date and fertile window to maximize your chances of conception or practice natural family planning awareness.
Cycle Information
Estimated Ovulation Date
May 15
Your most fertile day
Your 6-Day Fertile Window
These are your most fertile days. Conception is most likely to occur if you have intercourse during this window, especially 1-2 days before ovulation.
Understanding Ovulation and Fertility
Ovulation is when your ovary releases a mature egg, which travels down the fallopian tube where it can be fertilized by sperm. This typically occurs about 14 days before your next period starts. The egg survives for only 12-24 hours after release, but sperm can live in the reproductive tract for up to 5 days, creating a 6-day "fertile window" when pregnancy is possible.
The Fertile Window
Your fertile window includes the 5 days leading up to ovulation plus ovulation day itself. Pregnancy is most likely when intercourse occurs in the 2 days before ovulation. This is because sperm need time to travel and "capacitate" (prepare for fertilization), and the egg is only viable for about 24 hours after release.
Signs of Ovulation
Cervical Mucus Changes: Around ovulation, cervical mucus becomes clear, stretchy, and slippery - similar to raw egg whites. This "fertile quality" mucus helps sperm survive and swim toward the egg.
Basal Body Temperature (BBT): Your BBT rises slightly (0.5-1°F) after ovulation due to progesterone. Charting BBT can confirm ovulation occurred but doesn't predict it in advance.
Ovulation Pain (Mittelschmerz): Some women feel mild cramping or pain on one side of the pelvis during ovulation. This is normal and harmless.
LH Surge: Luteinizing hormone (LH) surges 24-36 hours before ovulation. Ovulation predictor kits detect this surge in urine.
Tracking Methods
Ovulation Predictor Kits (OPKs): Most accurate method. Test urine daily starting about 5 days before expected ovulation. Positive result indicates ovulation in 24-36 hours.
Fertility Apps: Track cycle patterns over time. More accurate with several months of data. Some apps integrate with BBT thermometers.
Fertility Monitors: Advanced devices that track hormones and other fertility signs. Expensive but very accurate.
Cervical Mucus Observation: Free method that requires learning to recognize fertile mucus. Effective when practiced consistently.
Factors Affecting Ovulation
Stress, illness, weight changes, intense exercise, travel, and irregular sleep can delay or prevent ovulation. Polycystic ovary syndrome (PCOS), thyroid disorders, and other medical conditions can affect ovulation regularity. If you have very irregular cycles or haven't conceived after 6-12 months of trying, consult a fertility specialist.
Important Disclaimer
Not for Contraception: This calculator should NOT be used to prevent pregnancy. Ovulation timing varies between cycles, and this method has a high failure rate for birth control.
For Conception: These are estimates based on average cycles. Individual ovulation timing varies. For best results, combine calendar tracking with ovulation predictor kits or other methods.
Seek Medical Advice: If you have irregular cycles, haven't conceived after 6-12 months of trying (6 months if over 35), or have concerns about fertility, consult a healthcare provider or fertility specialist.
Frequently Asked Questions
When do I ovulate?
Ovulation typically occurs 14 days before your next period. With a 28-day cycle, you ovulate around day 14. With a 30-day cycle, around day 16.
What is the fertile window?
The fertile window is the 6-day period when pregnancy is possible - 5 days before ovulation plus ovulation day. Sperm can survive up to 5 days in the reproductive tract.
What are signs of ovulation?
Signs include: clear, stretchy cervical mucus (egg-white consistency), mild pelvic pain on one side (mittelschmerz), increased libido, slight basal body temperature rise.
Can ovulation calculators prevent pregnancy?
No. Ovulation calculators are estimates and not reliable for contraception. Ovulation timing varies between cycles. Use reliable birth control methods to prevent pregnancy.
How can I track ovulation accurately?
Most accurate methods: ovulation predictor kits (detect LH surge), basal body temperature charting, cervical mucus monitoring. Combine multiple methods for best accuracy.