Estimate your most fertile days and likely ovulation date based on your cycle and luteal phase length.
How it works
- Enter the date of your last period.
- Indicate your cycle and luteal phase lengths.
- The calculator establishes your primary fertile window based on luteal estimates.
Frequently asked questions
When am I most fertile?
The two to three days before ovulation are typically the most fertile, as the egg and surviving sperm overlap.
How reliable is this for irregular cycles?
Less reliable — irregular cycles shift ovulation unpredictably. Ovulation tests or tracking basal temperature add accuracy.
Can I use this to avoid pregnancy?
Calendar estimates alone are not a reliable contraceptive. Consult a healthcare provider about effective methods.