Ovulation & Period Tracker

Find your fertile window

28 days
—
MonTueWedThu FriSatSun
Period Predicted period Follicular phase Fertile window Most fertile day Luteal phase
— Most fertile day
— Fertile window
— Next period

Hover any day to see its phase. Estimates are a guide only, not medical advice.

How to use the ovulation calculator

  1. 1

    Enter your last period date

    Enter the first day of your last period. For example, if your last period began on the 12th and ended on the 17th, your first day is the 12th.

  2. 2

    Select your average cycle length

    Count the days between the first day of one period and the first day of the next. If March started on the 12th and April on the 10th, that's a 30-day cycle. Average 4–5 months for the most accurate reading.

  3. 3

    Calculate your window

    Hit calculate to see your ovulation date, fertility window and next period date. The fertile window holds your most fertile days — though these remain rough estimates and may vary.

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Quick tips

  • Track your menstrual cycle and any symptoms — cramping, breast tenderness, mood changes — to plan a pregnancy better.
  • Keep a rough graph of your ovulation days in mind and watch out for symptoms.
  • Track your basal body temperature for at least three cycles; you'll notice a rise of less than half a degree Fahrenheit just after ovulation.

FAQs

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Why is ovulation calculation important?

Knowing your ovulation helps you plan a pregnancy, avoid one, or keep track of symptoms like light spotting, breast tenderness, cramping, bloating or an increased sex drive. Understanding how your body works is key to staying healthy and informed.

How long do I ovulate?

Ovulation lasts about 12 to 24 hours once the ovary releases an egg. But because sperm can survive in the body for up to five days, the fertile window spans roughly six days — the five days before ovulation plus the ovulation day itself.

When should I see a doctor?

Consult a doctor if you have PCOD or thyroid issues, which can affect ovulation, or for any unusual change — a period preponed or delayed by more than a week, unusually light or heavy discharge, or excruciating pain.

What are the signs that I'm not ovulating?

Watch for irregular, extremely painful, or unusually heavy or light periods over the last few cycles, along with sudden changes such as weight gain, a drop in sex drive, extra body hair or acne.

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