Period Calculator

How It Works

• Next Period: Calculated as LMP + cycle length. Period end is start date + period length.
• Cycle Day: Shows which day of your cycle you're on today and how many days remain.
• Ovulation: Estimated at cycle length − 14 days from LMP (standard formula).
• Fertile Window: Typically 5 days before to 1 day after ovulation.
• Irregular Cycles: Enter shortest and longest cycles to see prediction ranges.