Cycle Inputs
Enter your last period date, cycle length and tracking details to estimate ovulation and fertile days.Upcoming Fertile Windows
Next cycles| Cycle | Period | Fertile Window | Ovulation | Best Days | Test Date |
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How This Ovulation Calculator Works
This ovulation calculator estimates ovulation by using the first day of your last period, your average cycle length and your luteal phase. Ovulation is commonly estimated by counting back from the expected next period.
The fertile window is shown as a range because sperm can survive for several days and ovulation timing can vary. For better accuracy, combine calendar estimates with ovulation tests, cervical mucus tracking or basal body temperature patterns.
Window
Fertile Window
The fertile window highlights the days when conception is more likely.
Timing
Ovulation Date
Ovulation is estimated from cycle length and luteal phase.
Accuracy
Tracking Methods
Ovulation tests and symptoms can improve accuracy compared with calendar estimates alone.
Important: This calculator gives estimates only. It should not be used as contraception, diagnosis or medical advice. If cycles are very irregular, painful or absent, speak with a qualified healthcare professional.
Ovulation Result
Estimated fertility timeline
Fill in the calculator to estimate your ovulation date and fertile window.
Pregnancy Test-
Implantation Window-
Current Cycle Day-
Confidence-
Cycle Breakdown
Cycle length0 days
Luteal phase0 days
Period length0 days
Fertile days0 days
Method-
Useful Notes
- The fertile window usually includes the five days before ovulation and around one day after.
- Irregular cycles make calendar predictions less reliable.
- Pregnancy tests are usually more reliable from the expected period date.
- This calculator is not contraception or medical advice.