Period Calculator
Predict your next period, ovulation day, and fertile window. Save your cycle history and track patterns over time.
Cycle Information
Next period starts
Jun 6, 2026
Estimated ovulation day
May 23, 2026
Fertile window
May 18, 2026 – May 23, 2026
✨ You are currently fertile
Frequently Asked Questions
How accurate is this period calculator?
It's very accurate if you have a regular cycle (21–35 days). For irregular cycles, predictions are estimates. Track over several months for better accuracy.
What is a normal cycle length?
Typical range is 21–35 days, with 28 days being average. Variations of up to 7 days are common.
When do I ovulate?
Ovulation usually occurs 14 days before your next period. For a 28‑day cycle, that's day 14 (counting from period start).
Can I get pregnant outside the fertile window?
The fertile window (5 days before ovulation + ovulation day) is the only time pregnancy can occur. Sperm lives up to 5 days.
What if my cycles are irregular?
Use this tool as a guide. For irregular cycles, consider tracking basal body temperature or using ovulation kits.