Period Calculator
Track your menstrual cycle and predict your next period dates. Get insights into your cycle patterns and plan ahead with accurate period predictions.
Cycle Information
Enter the first day of your most recent period
Most cycles are 21-35 days. Average is 28 days.
How many days your period typically lasts (3-7 days is normal)
How many future periods to calculate
How consistent are your cycle lengths?
Period Predictions
Period Calendar
Understanding Your Menstrual Cycle
Cycle Phases
The lining of the uterus sheds, resulting in menstrual bleeding.
Eggs mature in the ovaries while estrogen levels rise.
A mature egg is released from the ovary.
The uterine lining thickens in preparation for potential pregnancy.
Normal Cycle Variations
Normal cycles range from 21-35 days, with 28 days being average.
Normal periods last 3-7 days, with 5 days being typical.
Flow can vary from light to heavy and may change throughout your period.
Some variation (±2-3 days) is normal, especially during teens and perimenopause.
Period Tracking Tips
What to Track
- First day of each period
- Last day of each period
- Flow intensity (light, medium, heavy)
- Symptoms (cramps, mood changes, etc.)
- Any spotting between periods
- Physical symptoms (bloating, breast tenderness)
Tracking Methods
- Period tracking apps
- Calendar marking
- Journal or diary
- Wearable devices
When to See a Doctor
- Periods suddenly become irregular
- Periods stop for more than 3 months
- Periods last longer than 7 days
- Extremely heavy bleeding
- Severe pain that interferes with daily activities
- Bleeding between periods
- Periods occur more than every 21 days
- Periods occur less than every 35 days
Benefits of Tracking
- Better preparation and planning
- Early detection of irregularities
- Understanding your body's patterns
- Helpful information for healthcare providers
Example Calculation
Last Period: January 1, 2024 • Cycle Length: 28 days • Period Length: 5 days
Predictions:
• Next period: January 29, 2024
• Period duration: January 29 - February 2, 2024
• Following period: February 26, 2024
• Third period: March 25, 2024
Cycle Information:
• Cycle type: Normal (28 days)
• Annual periods: ~13 periods
• Days between periods: 23 days
• Ovulation: Around January 15, 2024
Frequently Asked Questions
How accurate are period predictions?
Period predictions are most accurate for women with regular cycles. The calculator provides estimates based on your average cycle length, but actual dates may vary by 1-3 days due to natural fluctuations.
What if my cycles are irregular?
If your cycles vary significantly, predictions become less reliable. Track your periods for several months to identify patterns, and consider consulting a healthcare provider if irregularity is concerning.
Can stress affect my cycle?
Yes, stress, illness, travel, weight changes, and other factors can affect cycle timing. This is why some variation in cycle length is normal and expected.
Related Calculators
Ovulation Calculator
Calculate fertile window and ovulation date
Pregnancy Calculator
Calculate due date and pregnancy timeline
Pregnancy Weight Gain
Calculate healthy weight gain during pregnancy
BMI Calculator
Calculate your Body Mass Index
Calorie Calculator
Calculate daily calorie needs
Age Calculator
Calculate precise age and dates