Ovulation Calculator
Estimate ovulation date and fertile window from cycle timing.
This page is an editable estimator with realistic defaults so you can model your own situation in minutes.
Estimated ovulation date is next period date minus 14 days; fertile window is roughly the five days before ovulation through ovulation day.
Treat the result as a planning estimate and verify important numbers with the relevant official source before acting.
| Cycle length | 28 days | |
|---|---|---|
| Ovulation assumption | About 14 days before next period |
Assumptions
- Ovulation can vary from cycle to cycle.
- This calculator does not confirm ovulation or fertility.
How this calculator works
Formula used
Estimated ovulation date is next period date minus 14 days; fertile window is roughly the five days before ovulation through ovulation day.
Example calculation
Plug in your own numbers and the result updates instantly. Estimated ovulation date is next period date minus 14 days; fertile window is roughly the five days before ovulation through ovulation day.
Ovulation Calculator FAQ
Is this ovulation calculator medical advice?
No. It is an educational estimate only and does not replace an OB-GYN, midwife, fertility specialist, pediatric clinician, or emergency care.
Why might my actual dates or recommendations differ?
Cycle length, ovulation timing, ultrasound dating, implantation timing, multiples, medical history, and clinician judgment can change pregnancy and fertility estimates.
Should I confirm results with a clinician?
Yes. Confirm pregnancy dating, weight gain, cycle concerns, fertility timing, or health decisions with a qualified healthcare professional.