Missed Period Calculator
Cycle tracking
Missed Period Calculator
Enter the first day of your last period and your average cycle length to see your expected date, exactly how late you are (if at all), and what’s worth doing next.
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Expected period date
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Status
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About testing: a home pregnancy test is generally
most reliable from the day a period is due, and more reliable
again with each extra day past that if the first result is
negative and your period still hasn’t arrived.
Common reasons for a late or missed period
A late period has many possible causes beyond pregnancy, and often no single obvious one:
- Pregnancy — the most commonly considered cause once other explanations are ruled out
- Stress — can delay ovulation and, in turn, the next period
- Significant weight change or restrictive eating — can disrupt the hormones that regulate the cycle
- Intense or sudden increases in exercise — common in athletes and can suppress ovulation
- Illness — even a short-term illness can push a cycle off schedule
- Starting, stopping, or switching hormonal birth control — cycles often take a few months to settle after a change
- PCOS (polycystic ovary syndrome) — a common cause of irregular or unpredictable cycles
- Thyroid conditions — both an underactive and an overactive thyroid can affect cycle regularity
- Perimenopause — cycles often become irregular in the years leading up to menopause
- Breastfeeding — can delay the return of regular periods after childbirth
This list is educational, not a way to self-diagnose — a late period with an unclear cause is worth mentioning to a doctor, especially if it keeps happening.
Seek medical care promptly for severe pelvic or
abdominal pain, heavy bleeding, fainting, or dizziness, regardless
of how late your period is or what a test shows. If your period
is more than a week or two late with a negative test and no clear
explanation, or if this keeps happening cycle after cycle, it’s
worth checking in with your doctor.