Nigeria's most detailed ovulation & fertility calculator. Enter your cycle details and instantly get your full fertility calendar, peak day, and personalised conception guidance.
Medically accurate100% privateWorks offline once loadedNo data stored
Your Cycle Details
All information stays on your device — nothing is sent to any server.
The day your most recent period started
28days
Most women have cycles of 21–35 days. Average is 28.
How long your period usually lasts
3cycles
Plan ahead — up to 6 cycles
Your Fertility Calendar
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Period starts
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🌱
Fertile window opens
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✦
Peak ovulation day
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Highest chance to conceive
📅
Next period expected
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Your Fertility Calendar
Visual month-by-month view of your cycle phases
Period
Fertile days
Peak ovulation ✦
Luteal phase
Today
Your Cycle Phase Timeline
Visual breakdown of each phase of your menstrual cycle
Daily Conception Probability
Approximate likelihood of conception on each day of your fertile window — based on published fertility research
Future Cycle Predictions
Plan ahead with predictions for your upcoming cycles
Cycle
Period Starts
Fertile Window
Peak Ovulation
Next Period
Days Away
Personalised Conception Tips
Evidence-based guidance to maximise your chances
Save or share your fertility calendar
Frequently Asked Questions
Everything you need to know about ovulation and fertility
This calculator uses the standard clinical method: ovulation is estimated to occur 14 days before your next expected period. Research shows this is accurate within ±2 days for women with regular cycles of 21–35 days. Women with irregular cycles may experience more variation. For the highest accuracy, combine this calculator with basal body temperature (BBT) tracking or ovulation predictor kits (OPKs).
The fertile window is the period during which pregnancy is possible. It lasts approximately 6 days — the 5 days before ovulation plus the day of ovulation itself. This is because sperm can survive inside the female reproductive tract for up to 5 days, while an egg survives only 12–24 hours after release. Having intercourse in the days leading up to ovulation maximises your chances.
The peak ovulation day (highlighted in rose on your calendar) is the single best day to try to conceive — conception probability can be as high as 33% on this day. However, the 2 days immediately before ovulation are almost equally effective and are sometimes considered optimal because sperm are already present when the egg is released. Having intercourse every 1–2 days throughout your fertile window gives the best overall chance.
Yes, but with caution. Enter your average cycle length over the last 3–6 months. If your cycles vary by more than 7 days regularly, the predictions will be less precise. Women with irregular cycles benefit most from additional tracking methods: basal body temperature charting, cervical mucus observation, and ovulation predictor kits. If you've had irregular cycles for more than 3 months, consider speaking with a gynaecologist.
Common physical signs of ovulation include: egg-white cervical mucus (clear, stretchy discharge), a slight rise in basal body temperature (0.2–0.5°C), mild one-sided pelvic pain or cramping (Mittelschmerz), breast tenderness, increased libido, and a slight spotting. Not all women experience all signs. Tracking BBT daily (first thing in the morning before rising) over several cycles gives you a reliable pattern.
The probability is very low but not zero. Cycle length can vary month to month, meaning ovulation may occur earlier or later than predicted. Stress, illness, travel, or changes in routine can shift your ovulation date. This is why pregnancy is possible even during what appears to be a "safe" period. This calculator is intended for conception planning — it should not be used as a contraceptive method.
Several nutrients play key roles in reproductive health. Folic acid (400–800mcg/day) is essential before and during early pregnancy. Vitamin D supports hormone regulation. Omega-3 fatty acids support egg quality. CoQ10 may improve egg and sperm quality. Iron, B12, and zinc are important for a healthy menstrual cycle. Always consult a healthcare provider before starting any supplement regimen.
Understanding Your Ovulation Cycle
Ovulation is the release of a mature egg from one of your ovaries — the central event of your menstrual cycle and the key to conception. Understanding exactly when ovulation occurs gives you the knowledge to either plan a pregnancy or simply understand your own body better.
How the Menstrual Cycle Works
A typical menstrual cycle is divided into four phases. The menstrual phase (days 1–5) is when your period occurs as the uterine lining sheds. The follicular phase (days 1–13) overlaps with your period and continues as follicles in your ovaries mature. The ovulatory phase (around day 14 in a 28-day cycle) is when a mature egg bursts from its follicle. The luteal phase (days 15–28) follows ovulation as the corpus luteum produces progesterone to prepare the uterus for a potential pregnancy.
When Does Ovulation Actually Happen?
Ovulation typically occurs 12 to 16 days before the start of your next period — not necessarily on day 14 of your cycle. This distinction is critical: if you have a 35-day cycle, you likely ovulate around day 21, not day 14. This calculator accounts for your specific cycle length to give you a personalised prediction.
The Science Behind the 6-Day Fertile Window
Research published in the New England Journal of Medicine established that conception is possible on any of the six days ending on the day of ovulation. Sperm can survive in the fallopian tubes for up to five days, while an egg lives only 12–24 hours after ovulation. This means having intercourse before ovulation — not just on the day of — is equally or more effective for conception.
Support Your Fertility Journey with Quality Supplements
Explore our range of women's health supplements — from folic acid to prenatal vitamins — formulated to support reproductive health.
For the most accurate tracking, combine this calculator with basal body temperature (BBT) charting — taking your temperature every morning before getting out of bed. A slight rise of 0.2–0.5°C typically indicates ovulation has just occurred. Over 2–3 cycles, you'll identify a reliable pattern unique to your body.
Ovulation predictor kits (OPKs) detect the luteinizing hormone (LH) surge that occurs 24–36 hours before ovulation — giving you advance warning of your peak day. Used alongside this calendar, they provide excellent precision for conception planning.
