Ovulation Calculator
Predict your fertile window and next ovulation date.
About this tool
This tool predicts your most fertile days based on a standard luteal phase of 14 days. Ovulation typically happens about 14 days before your next period, so the calculation works backward from your expected next cycle.
The fertile window includes the 5 days before ovulation and ovulation day itself, since sperm can survive that long inside the reproductive tract.
Frequently asked questions
How accurate is this for irregular cycles?
Cycle-based predictions assume regularity. If your cycles vary by more than a few days, ovulation predictor kits (LH urine tests) or tracking basal body temperature give more reliable confirmation.
When should I see a clinician about fertility?
If you've been trying for 12 months without success — or 6 months if you're over 35 — a fertility evaluation is reasonable.
Can I get pregnant outside the fertile window?
It's much less likely but not impossible, especially if your cycles are irregular or you ovulate earlier than predicted.
⚕️ Educational only — not a substitute for professional medical advice, diagnosis, or treatment. In an emergency call your local emergency services.