Period Calculator | Next Period Date and Cycle Timeline
Estimate the next period start and end date from last period date, cycle length, and period length for basic cycle planning.
Estimate Your Next Period Date
Enter the first day of your last period, average cycle length, and period length to estimate the next start date, end date, and basic cycle timeline.
Cycle Predictions Are Estimates
Stress, illness, travel, sleep changes, medication, hormonal contraception, postpartum changes, and health conditions can shift real cycle dates.
When a Period Calculator Helps
Use it for calendar planning, packing, travel, symptom tracking, and personal reminders. Do not use estimated dates as medical advice or contraception guidance.
About This Tool
Period Calculator predicts the start dates of upcoming menstrual cycles based on the first day of your last period and your average cycle length. It helps plan ahead for events, travel, and appointments.
When to Use It
Use this to anticipate upcoming period dates when planning a holiday or event, when tracking your cycle for health monitoring, or when preparing information for a doctor's appointment about cycle regularity.
How to Use
- Enter the first day of your last period.
- Enter your average cycle length in days.
- Click Calculate to see the predicted start dates for the next several cycles.
Frequently Asked Questions
How accurate are the predictions?
Predictions are based on your entered average cycle length. Actual dates can vary due to stress, illness, diet, and hormonal changes. Track several cycles for a more accurate personal average.
What is the average menstrual cycle length?
The average cycle is 28 days but a normal range is 21 to 35 days. Cycles shorter than 21 or longer than 35 days may warrant a medical consultation.
Can I use this instead of a period tracking app?
This calculator provides quick predictions. A dedicated app with daily logging gives more accurate personalised predictions over time.