When is the best time to get pregnant?

The best time is the 6-day fertile window: the 5 days leading up to ovulation plus the day of ovulation itself. Sperm can survive up to 5 days in the reproductive tract, while an egg is viable for 12–24 hours after release.

How do I know when I ovulate?

This calculator gives an estimate based on your cycle length. For confirmation, use an ovulation predictor kit (OPK) to detect the LH surge, or track basal body temperature (BBT) — which rises ~0.2°C after ovulation.

What if my cycle is irregular?

Irregular cycles make calendar-based prediction less reliable. Ovulation predictor kits, BBT charting, or monitoring cervical mucus are more accurate methods. Talk to your OB-GYN if cycles vary by more than 7 days regularly.

Can I get pregnant outside the fertile window?

It's very unlikely but possible, since cycle length can vary month to month. No calendar method is 100% reliable for either achieving or avoiding pregnancy.

Ovulation Calculator

Quick answer: Enter your last period date and cycle length to see your estimated ovulation date and the 6-day fertile window when conception is most likely.

Ovulation typically occurs about 14 days before your next period — so for a 28-day cycle, that's day 14, and for a 35-day cycle, it's day 21. Your fertile window spans the 5 days before ovulation plus ovulation day itself. This calculator estimates your fertile window based on your last menstrual period date and average cycle length.

Last reviewed: April 2026Report an error

First Day of Last Period

Cycle Length (days)

Estimated Ovulation Date

May 28, 2026

Your estimated ovulation date is May 28, 2026. Your fertile window is May 23, 2026 – May 29, 2026. Next period expected around Jun 11, 2026.

Fertile Window (6 days)

May 23, 2026 → May 29, 2026

Days Until Ovulation

9 days

Next Period

Jun 11, 2026

How to Use This Ovulation Calculator

1Enter the first day of your most recent period.
2Enter your average cycle length (count from day 1 of one period to day 1 of the next).
3Read your estimated ovulation date (most fertile day).
4Note the 6-day fertile window — the 5 days before ovulation plus ovulation day.
5Track 2–3 cycles to identify your personal pattern; use ovulation predictor kits (OPKs) for confirmation.

Frequently Asked Questions

: The best time is the 6-day fertile window: the 5 days leading up to ovulation plus the day of ovulation itself. Sperm can survive up to 5 days in the reproductive tract, while an egg is viable for 12–24 hours after release.
: This calculator gives an estimate based on your cycle length. For confirmation, use an ovulation predictor kit (OPK) to detect the LH surge, or track basal body temperature (BBT) — which rises ~0.2°C after ovulation.
: Irregular cycles make calendar-based prediction less reliable. Ovulation predictor kits, BBT charting, or monitoring cervical mucus are more accurate methods. Talk to your OB-GYN if cycles vary by more than 7 days regularly.
: It's very unlikely but possible, since cycle length can vary month to month. No calendar method is 100% reliable for either achieving or avoiding pregnancy.

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Ovulation Calculator

How to Use This Ovulation Calculator

Frequently Asked Questions

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