Period Calculator – Next Period Date Predictor
Predict your next period date and track your menstrual cycle.
❤️ Health📐
First day of last period (YYYY-MM-DD)
Cycle length (days)
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Period Calculator – Next Period Date Predictor | result |
Step-by-Step Examples
Example 1
March 1 start, 28-day cycle
- Next period: March 29 | Following: April 26
- Ovulation: March 15
✓ March 29 next period
Example 2
March 1 start, 32-day cycle
- Next period: April 2 | Following: May 4
- Ovulation: March 19
✓ April 2
Example 3
Irregular cycle estimate
- Use average of last 3 cycles for best estimate
✓ Use average cycle length
Real-World Applications
Women
Predict and track menstrual cycle.
Health Trackers
Know when to expect your period.
Gynecologists
Advise patients on cycle tracking.
Couples
Plan around fertility window.
Common Mistakes to Avoid
⚠️
Cycle length varies
Stress, illness, travel, and hormonal changes can shift cycle. Log multiple cycles for accuracy.
⚠️
Not a pregnancy test
If period is late more than 1 week, take a pregnancy test and consult a doctor.
Frequently Asked Questions
Normal cycle length? ▾
21-35 days is normal. 28 days is average. Anything outside 21-35 should be discussed with a doctor.
What causes late period? ▾
Stress, illness, excessive exercise, weight changes, hormonal imbalance, pregnancy, or perimenopause.
Period tracking apps? ▾
Flo, Clue, Ovia, and Natural Cycles are popular. Use one consistently for better cycle prediction accuracy.