Health · Free tool
Fertility Window
Ovulation usually 14 days before next period. Sperm survives ~5 days in cervix. Egg survives ~24 hours. Combined fertile window: 5 days before + day of + 1 day after ovulation.
days
Most fertile
15 May 2026 – 21 May 2026
Ovulation
20 May 2026
Next period
3 Jun 2026
FAQ
Calendar method accuracy?
Per-cycle ~60-70%. Best for couples planning pregnancy. Less reliable as contraception.
Irregular cycles — does this work?
Less reliable. Track 6+ months for average. PCOS makes calendar method unreliable. See a fertility specialist.
Sex during fertile window — chance of pregnancy?
Per-cycle: ~25%. Cumulative: 60-80% within 6 months, 90% within 12.