🌸 Ovulation Calculator
Predict your most fertile days and ovulation date based on your menstrual cycle.
How to Use This Calculator Effectively
This calculator uses the standard Ogino-Knaus method: ovulation is estimated to occur 14 days before your next period. Enter the first day of your most recent period and your average cycle length to get your most likely ovulation window and peak fertile days.
For the most accurate results, track your cycles for 3–6 months and use your average cycle length. If your cycles are irregular (varying by more than 7 days), consider combining this calculator with additional tracking methods like basal body temperature (BBT) charting or ovulation predictor kits (OPKs).
Physical Signs of Ovulation to Watch For
- Changes in cervical mucus — Around ovulation, discharge becomes clear, slippery, and stretchy — similar to raw egg whites. This is often the most reliable physical sign.
- Mild pelvic pain — Some women feel a brief, one-sided ache called mittelschmerz ("middle pain" in German) when an egg is released.
- Slight rise in basal body temperature (BBT) — After ovulation, BBT rises 0.2–0.5°C due to progesterone. Track daily with a basal thermometer before getting out of bed.
- Increased libido — Hormonal changes around ovulation naturally increase sex drive in many women.
- Breast tenderness — Mild soreness or sensitivity can occur around the time of ovulation.
Understanding Your Cycle
A typical menstrual cycle has four phases:
| Phase | Days (28-day cycle) | What Happens |
|---|---|---|
| Menstruation | Days 1–5 | Uterine lining sheds |
| Follicular | Days 1–13 | Follicles develop; estrogen rises |
| Ovulation | Day 14 | Egg is released — peak fertility |
| Luteal | Days 15–28 | Progesterone rises; uterus prepares |
Frequently Asked Questions
When do I ovulate?
Ovulation usually occurs ~14 days before your next period. For a 28-day cycle, that's day 14. The fertile window is the 5 days before ovulation plus ovulation day.
How long is the fertile window?
About 6 days: 5 days before ovulation + ovulation day. Sperm can survive 3–5 days; the egg is viable 12–24 hours. The 2–3 days before ovulation are most fertile.
What are signs of ovulation?
Clear stretchy mucus (egg-white texture), mild pelvic cramps, slight temperature rise, increased libido, and breast tenderness are common signs.
Is this calculator accurate?
It provides estimates based on average cycle patterns. Most accurate for regular cycles. Irregular cycles make prediction harder. For fertility treatment, always work with a healthcare provider.