Ovulation Calculator

Track your fertile days and find the best time to conceive

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Ovulation Calculator — Quick 8‑Section Guide

1) Core idea

Ovulation typically occurs lutealPhase days before your next period (≈14 by default). We use your last period, cycle length, and optional luteal phase to map fertile days.

2) Flow you can trust

  1. Enter LMP, cycle length, and optional luteal phase.
  2. We project the next period, subtract the luteal phase to find ovulation.
  3. We highlight a 6‑day fertile window: 5 days before ovulation + ovulation day.

3) Sanity checks

  • Sperm can live up to ~5 days; the egg ~12–24 hours.
  • Luteal phase is usually the most consistent part of the cycle.

4) Shortcuts

  • No luteal data? Use 14 days as a reasonable default.
  • Best conception odds: 2–3 days before ovulation and on ovulation day.

5) Pitfalls

  • Irregular cycles lower prediction accuracy—consider OPKs/BBT tracking.
  • Stress, illness, and travel can shift ovulation timing.

6) Micro examples

  • 28‑day cycle, LMP Jan 1 → Ovulation ≈ Jan 14; fertile window Jan 9–14.
  • 32‑day cycle, luteal 14 → Ovulation ≈ Day 18; fertile window Days 13–18.

7) Mini‑FAQ

  • Can I conceive outside the window? It’s unlikely but timing can vary by a few days.
  • Is this medical advice? No—use alongside professional guidance if trying to conceive.

8) Action tip

Combine this calendar with OPKs and cervical‑mucus checks for higher accuracy.