Period Calculator: Track Menstrual Cycle & Ovulation

How to use

Track your menstrual cycle in a few simple steps.

1. Enter last period date

Input the first day of your last menstrual period.

2. Enter cycle length

Provide your average cycle length in days (typically 28 days).

3. Enter period duration

Input how many days your period typically lasts.

4. View predictions

Review your next period date, fertile window, and ovulation day.

FAQs

How accurate is a period calculator?

Period calculators are estimates based on average cycle patterns. Actual dates may vary due to stress, health changes, or natural cycle variations.

What is a normal menstrual cycle length?

A normal cycle ranges from 21 to 35 days, with 28 days being average. Cycles may vary by a few days each month.

What is the fertile window?

The fertile window is typically the 5-6 days leading up to and including ovulation. This is when conception is most likely to occur.