Ovulation Calculator
Ovulation is when an ovary releases an egg — the most fertile point of your cycle — and it happens about 14 days before your next period. Enter your last period and cycle length to see the ovulation day and fertile window for the coming months.
Your numbers
Result
- Fertile window
- —
- Next period
- —
How the ovulation day is estimated
Ovulation lands roughly 14 days before the next period starts, so the estimate is ovulation = cycle start + (cycle length − 14). On a 28-day cycle that is about day 14; on a 32-day cycle, about day 18. The fertile window covers the 5 days before ovulation plus the day after, because sperm can survive several days while the egg lives about one.
Planning across several cycles
The table projects the next three cycles so you can plan ahead. Because real cycle length varies from month to month, treat the dates as estimates — the more regular your cycle, the more reliable they are. Logging the start of each period for a few months sharpens the prediction considerably.
Signs that confirm ovulation
Your body gives clues beyond the calendar: cervical mucus turns clear and stretchy near ovulation, basal body temperature rises a few tenths of a degree just after, and some people feel a light one-sided twinge. Drugstore ovulation tests detect the LH hormone, which surges shortly before you ovulate — useful when cycles are irregular.
Informational and educational result. Not a substitute for professional advice.
Frequently asked questions
Sources
Embed this calculator
Copy the code and paste it into your site or blog. Credit with a link back to Contania is included, and the height adjusts itself.
<iframe src="https://contania.app/embed/pregnancy/ovulation" title="Ovulation Calculator — fertile days for the next cycles" width="100%" height="720" loading="lazy" style="border:1px solid #e5e0d8;border-radius:12px;max-width:640px"></iframe>
<script>window.addEventListener("message",function(e){if(e.data&&e.data.type==="contania:embed-height"){var f=document.querySelector('iframe[src="https://contania.app/embed/pregnancy/ovulation"]');if(f){f.style.height=e.data.height+"px"}}});</script>Related calculators
BMI
Calculate your BMI (Body Mass Index), see the WHO classification and the healthy weight range for your height. Switch between metric (kg/cm) and imperial (lb/in).
CalculateBMR
Calculate your BMR (basal metabolic rate) with the Mifflin-St Jeor equation — the calories your body burns at rest — and see your daily burn at each activity level.
CalculateWeeks to Months
Convert your week of pregnancy into months, following the prenatal convention where 40 weeks equals 9 months, and see which trimester it falls in.
CalculatePregnancy Weight Gain
Find the healthy amount of weight to gain in pregnancy based on your pre-pregnancy BMI, using the IOM ranges — plus the gain expected by your current week.
Calculate