月經週期計算器

追蹤月經週期並預測下次月經和排卵日

First day of last period

Average cycle length (days)

Estimated next period

2026年10月4日

Estimated ovulation

2026年9月20日

Estimated fertile window

2026年9月15日 – 2026年9月21日

This is a calendar estimate. Ovulation can vary from cycle to cycle and estimates are less reliable with irregular cycles, lactation, perimenopause, illness, or medicines. Do not use it for contraception, pregnancy confirmation, or infertility diagnosis.

Seek medical advice for a sudden cycle change, no period for 3 months when not pregnant, very heavy bleeding, fainting, or severe pelvic pain.