Next Period Date Calculator — Predict Your Next Period
Accurately predict your next period date based on your last period and cycle length.
Frequently Asked Questions — Menstrual Cycle Calculator
How do I calculate when my next period will come?+
Add your cycle length (e.g., 28 days) to the first day of your last period. For example: last period March 1st + 28 days = next period March 29th. Most apps do this calculation automatically. Track several cycles to determine your average cycle length.
Why is my period late?+
Common causes of a late period: stress (most common cause for irregular cycles), travel/time zone changes, significant weight loss or gain, intense exercise changes, new medications (especially hormonal), PCOS (polycystic ovary syndrome), thyroid dysfunction, perimenopause (40+), and early pregnancy. A period up to 7 days late is considered within normal variation.
Is a 28-day cycle the most common?+
No — 28 days is just an average. A large Oxford University study of 600,000 cycles found that cycles naturally range from 23-35 days and vary month to month. A healthy normal cycle can be anywhere from 21-38 days. Less than 20% of women have exactly 28-day cycles.