Ovulation Calculator
Calculate your ovulation date and fertile window. Enter the first day of your last period and cycle length to identify your most fertile days for conception. Free, no sign-up required.
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21 days35 days
How Ovulation Works
Ovulation occurs when an ovary releases an egg, which happens once per menstrual cycle. The egg travels down the fallopian tube where it may be fertilized by sperm. Ovulation typically occurs 14 days before your next period, regardless of cycle length.
🌸 Fertile Window
5 days before ovulation to 1 day after. Best time to conceive.
🥚 Ovulation Day
Egg release, survives 12-24 hours. Peak fertility day.
Frequently Asked Questions
How is ovulation calculated?▾
Ovulation is calculated as 14 days before your next period (for a 28-day cycle, that's day 14). The fertile window is 5 days before ovulation to 1 day after — this is when you're most likely to conceive. Enter your last period date and cycle length to see your personalized dates.
What is the fertile window?▾
The fertile window is the 6-day period each month when you're most likely to get pregnant: 5 days before ovulation plus the day of ovulation. Sperm can live up to 5 days in the reproductive tract, and the egg lives 12-24 hours after release. This calculator shows your exact fertile window dates.
How accurate is ovulation calculation?▾
This calculator estimates ovulation based on average cycles. Actual ovulation can vary by days each cycle. For most accurate tracking, use ovulation predictor kits, track basal body temperature, or monitor cervical mucus. Women with irregular cycles may have less predictable ovulation.
What if my cycle isn't 28 days?▾
Adjust the cycle length slider to match your actual cycle (21-35 days is normal). Ovulation always occurs about 14 days before your period, so a 35-day cycle means ovulation around day 21, while a 21-day cycle means ovulation around day 7.
How do I know when I'm ovulating?▾
Signs of ovulation include: slight increase in basal body temperature, changes in cervical mucus (clear and stretchy), mild pelvic pain (Mittelschmerz), increased libido, and breast tenderness. Ovulation predictor kits can detect the LH surge that precedes ovulation by 24-36 hours.
When is the best time to conceive?▾
The best time to conceive is during your fertile window, especially the 2-3 days before ovulation and the day of ovulation. Having sex every 1-2 days during this window maximizes your chances. This calculator identifies your optimal dates based on your cycle.
How long does ovulation last?▾
Ovulation itself is brief — the egg is released and survives only 12-24 hours if not fertilized. However, the fertile window lasts 6 days because sperm can survive up to 5 days in the female reproductive tract. This means you can get pregnant from sex up to 5 days before ovulation.