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Menstrual Cycle Calculator

Predict period, ovulation day, fertile window and safe days

文件零上传 · 即用即删
Common cycles:
Cycles to show:Default 28-day cycle · Ovulation = 14 days before next period
Today's Status
Ovulation Day
Today is the predicted ovulation day
Today
2026-09-18 WeekFri

Cycle 1

2026-09-04 ~ 2026-10-01
Period
9/4 - 9/8total 5 days
WeekFri ~ WeekTue
Safe Days
9/9 - 9/12Safe Before Ovulation
Fertile Window
9/13 - 9/195 days before to 1 day after ovulation
Ovulation Day
9/18 WeekFri14 days before next period
Cycle Timeline
Day 1Day 28

Cycle 2

2026-10-02 ~ 2026-10-29
Period
10/2 - 10/6total 5 days
WeekFri ~ WeekTue
Safe Days
10/7 - 10/10Safe Before Ovulation
Fertile Window
10/11 - 10/175 days before to 1 day after ovulation
Ovulation Day
10/16 WeekFri14 days before next period
Cycle Timeline
Day 1Day 28

Cycle 3

2026-10-30 ~ 2026-11-26
Period
10/30 - 11/3total 5 days
WeekFri ~ WeekTue
Safe Days
11/4 - 11/7Safe Before Ovulation
Fertile Window
11/8 - 11/145 days before to 1 day after ovulation
Ovulation Day
11/13 WeekFri14 days before next period
Cycle Timeline
Day 1Day 28

Legend

Period
Fertile Window
Ovulation Day
Safe Days

This tool is for reference only

Introduction

Online period calculator. Based on the last menstrual date and cycle length, it predicts the next period, ovulation period, and safe period. Ideal for women's health management and pregnancy planning.

Usage

  1. 1选择上次月经开始的日期。
  2. 2输入平均月经周期天数（通常 21-35 天，默认 28 天）。
  3. 3输入每次月经持续天数（通常 2-7 天，默认 5 天）。
  4. 4系统自动计算并展示未来 3 个周期的预测，包括经期、排卵期、易孕期和安全期。

Tips

  • 本计算器基于平均周期推算，实际情况因人而异
  • 压力、饮食、运动、疾病等都可能影响月经周期
  • 排卵日通常在下次月经前 14 天左右
  • 易孕期为排卵日前 5 天至排卵日后 1 天

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