Period Calculator
Predict your next period date, track your menstrual cycle, and plan ahead for the next 6 months.
Input Parameters
Results
Tracking Your Menstrual Cycle
The average menstrual cycle is 28 days, but anything from 21–35 days is considered normal. Tracking your cycle helps predict periods, identify ovulation, and detect irregularities. Use a period tracking app for more detailed logs over time.
What is the Period Calculator?
The Period Calculator is a menstrual cycle tracking tool designed to predict the exact start date of your next period. It helps women proactively manage their health, plan vacations, and understand their natural biological rhythms.
How It Works (Formula)
The tool uses basic calendar arithmetic. It takes the start date of your last menstrual period (LMP) and simply adds the average length of your menstrual cycle to project future dates.
$$ \text{Next Period} = \text{LMP Start Date} + \text{Average Cycle Length} $$
Most cycles last between 28 and 32 days.
How to Use It
Select the first day of your last period from the calendar input, and enter your average cycle duration (e.g., 28 days). The calculator will instantly generate a 3-month forecast of your upcoming periods.