Period Calculator
About the Period Calculator
Tracking your menstrual cycle helps you predict upcoming periods, plan ahead, and notice any unusual changes in your cycle pattern.
Formula Used
Next Period = LMP + Cycle Length (days)
How It Works
This calculator adds your average cycle length to the start date of your last period to predict your next period, and projects the following two cycles as well.
Step by Step
- Enter the first day of your last period.
- Select your average cycle length and typical period duration.
- The calculator projects your next period and the following two cycles.
Worked Example
Example: LMP on 1 January, 28-day cycle:
Next period = 1 January + 28 days = 29 January
Frequently Asked Questions
What is a normal cycle length?
A typical menstrual cycle ranges from 21 to 35 days, with 28 days being the commonly cited average.
Why might my period come earlier or later than predicted?
Stress, illness, travel, weight changes, and hormonal fluctuations can all shift your cycle from month to month.
Can this calculator diagnose irregular periods?
No, it's a prediction tool only - consult a doctor if you notice persistent irregularity or unusual symptoms.