ezdodal logo

Ovulation Calculator

A free online ovulation calculator to track your fertile window and ovulation date. Enter your cycle to predict your most fertile days and next period dates for up to 6 months—no sign-up required.

Enter Basic Info

28days

Avg. 28 days

5days

Avg. 5 days

What is Ovulation Calculator?

A free online ovulation calculator you can use directly in your browser. Based on your menstrual cycle, it predicts your ovulation date and fertile window to help you identify the best days for conception. Use with basal body temperature tracking or ovulation kits for even better accuracy.

Understanding Ovulation / Fertile Window

The fertile window lasts about 6 days per cycle, considering the egg's 24-hour lifespan and sperm's ability to survive up to 5 days in the body. The day of ovulation and the 5 days before it are the peak time for conception. While cycles vary, the 'Luteal Phase' (time from ovulation to next period) is typically consistent at 14 days. By counting back 14 days from your next expected period, this tool can more accurately predict your ovulation date.

Key Features

  • Fertile window calculation based on Ogino Method
  • 6-month prediction of periods and ovulation
  • Auto-generate and save result image
  • Customizable cycle length and period duration
  • Intuitive date visualization
  • Mobile and Desktop optimized UI
  • Instant use without registration

Use Cases

  • Parents-to-be planning for pregnancy
  • Systematic management of menstrual cycles
  • Checking period dates before travel or events
  • Predicting ovulation pain or PMS timing
  • Reference for natural contraception (Do not rely solely)
  • Organizing cycle info before OB/GYN visit

Pro Tip: 4 Phases of Menstrual Cycle & Conception

Understanding your cycle helps layout your pregnancy plan. There are 4 main phases.

1. Menstrual Phase

The lining of the uterus sheds. This marks the start of a new cycle.

2. Follicular Phase

Follicles mature in the ovary. The uterine lining thickens to prepare for ovulation.

3. Ovulation Phase

The fertile window lasts about 6 days: 5 days before ovulation and the day of. Sperm survive up to 5 days, while eggs survive 12-24 hours. In a 28-day cycle, ovulation is around day 14. This tool estimates ovulation 14 days before the next period.

4. Luteal Phase

The follicle becomes the corpus luteum. The luteal phase is typically constant at 14 days. If not pregnant, menstruation begins again.

How to Use

  1. Select Last Period Date: Click the calendar icon to pick the start date of your last period.
  2. Set Cycle Details: Use sliders to set your average cycle length and period duration.
  3. View Results: Click the button to see ovulation, fertile window, and next period dates for 6 months.
  4. Save Image: Use the 'Save Image' button to save the 6-month prediction table to your photo gallery.

FAQ

This calculator uses the Ogino method, which is most accurate for regular cycles. If irregular, combine with ovulation test kits or doctor visits.

Ovulation is the single day the egg is released. The fertile window includes the 5-6 days around ovulation when pregnancy is possible due to sperm survival.

Clicking 'Save Image' will automatically save a clean image of your result table to your device's default downloads folder or photo gallery.

Ezdodal processes minimal information for user convenience, and all data is securely protected.

Yes, if you have a short cycle (under 21 days), your fertile window may start right as your period ends.

It varies, but typically clear mucus appears 2-3 days prior, and some feel lower abdominal pain or see temp changes on the day.