Ovulation Calculator: Track Your Fertile Window
Your Fertile Window Is Narrower Than You Think
An egg survives only 12–24 hours after ovulation. Sperm can survive up to 5 days in the reproductive tract. This means your fertile window is roughly 6 days: the 5 days before ovulation and the day of ovulation itself. Knowing when you ovulate is key for both conception and natural family planning.
How to Estimate Ovulation
| Method | How | Accuracy |
|---|---|---|
| Calendar method | Ovulation ≈ 14 days before next period | Moderate (assumes regular cycles) |
| Basal body temperature | Temp rises 0.2–0.5°C after ovulation | Confirms ovulation after it happens |
| Cervical mucus | Egg-white consistency = fertile | Good with practice |
| OPK (ovulation test strips) | Detects LH surge 24–36 hours before ovulation | High (most reliable home method) |
For Irregular Cycles
If your cycle varies by more than 7 days, calendar-based ovulation prediction becomes unreliable. In such cases, OPK strips or ultrasound monitoring (follicular study) are more reliable. Conditions like PCOS can cause irregular ovulation — consult a gynecologist for guidance.
Use the ovulation calculator to estimate your fertile window based on your cycle length and last period date.