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Ovulation & fertile window calculator

Pinpoint your most fertile days for the next three cycles, so you know exactly when to try.

Ovulation & fertile window calculator

Find your most fertile days for the next three cycles.

Estimated ovulation day
fertile window
best days to try
next period due
Your cycle length is outside the usual 21–35 day range.Predictions are less reliable with irregular cycles — this is common with PCOS and worth a check. Ovulation kits or a fertility consultation can pinpoint your timing.

Next three cycles

CycleFertile windowOvulationNext period

Based on ovulation about 14 days before your next period. Sperm can survive up to 5 days, so the fertile window starts before ovulation.

Understanding your fertile window

Ovulation usually happens about 14 days before your next period starts — so in a 28-day cycle that's around day 14, but in a 32-day cycle it's closer to day 18. The egg lives for about a day, while sperm can survive up to five, which is why the fertile window runs from roughly five days before ovulation to the day after.

The two days before ovulation and the day itself are the most fertile. If your cycles are irregular, the calendar method is less reliable — ovulation predictor kits, tracking cervical mucus, or a simple fertility work-up can help.

Questions, answered

What are my most fertile days?

The two days before ovulation and ovulation day itself. Having intercourse every 1–2 days across the whole fertile window gives the best chance.

Can I ovulate with irregular periods?

Yes, but the timing is unpredictable, and some cycles may not release an egg at all (common in PCOS). If your cycles vary a lot, an evaluation can find out what's happening and improve your chances.

How long should we try before seeing a doctor?

If you're under 35, about 12 months of trying; if 35–39, about 6 months; if 40 or over, see a specialist as soon as you start. Come earlier if you have irregular periods, known endometriosis, or previous miscarriages.

Does this calculator work for PCOS?

It gives an estimate, but PCOS cycles are often irregular and may not ovulate every month, so the calendar method can miss. A consultation with Dr. Ritika can map your ovulation properly and discuss simple treatments.

Want a doctor to confirm this?

Dr. Ritika sees patients at Cloudnine Hospital, Phase 3 Industrial Area, Mohali · Mon–Sat, 10 AM – 5 PM.

Tool logic reviewed by Dr. Ritika Gupta, MS (Obs & Gyn), FMAS, DMAS — last reviewed 2026-09-20. Uses standard clinical methods (e.g. Naegele's rule); results are estimates.

This tool is for general guidance and does not replace a personal consultation. Your dates will be confirmed by ultrasound. If you have urgent symptoms, seek care promptly.