personal cycle forecast · Generated Your 6-month forecast
Predicted period days, fertile window and ovulation — based on your average cycle.
Upcoming important dates — next 12 cycles
What "late" actually means
On a calendar, "late" simply means today is past the date your average cycle predicted. Clinically, a single period arriving a few days off schedule is normal variation; professional guidance generally treats a period as late once it is about a week or more past expected, and as a missed period once roughly 90 days have passed.
So a forecast that is two or three days "late" is usually just your body being your body — stress, a bad sleep week or a long flight can all shift ovulation, and ovulation timing is what moves the whole cycle.
Common reasons your period is late
The usual suspects, in rough order of how often they show up: psychological or physical stress; significant weight loss or gain; intense exercise; illness or travel; starting, stopping or missing hormonal birth control; breastfeeding and the postpartum months; perimenopause; conditions such as PCOS or thyroid imbalance — and, of course, pregnancy.
If there is any chance of pregnancy and you are around a week late, a home pregnancy test is usually reliable by then. If not, give it a couple of weeks and keep logging: one off-cycle rarely means anything, a pattern is what doctors care about.
What to do next
First, breathe — a late period is one of the most common reasons people search for health tools, and most causes are temporary. Second, take a test if pregnancy is possible. Third, keep tracking your cycles so you can tell a one-off from a pattern.
See a clinician if your period is absent for three months or more, your cycles suddenly become much more irregular, or you have red flags like very heavy bleeding, severe pain or fever.
How our late detection works
We compute your predicted start date as last period + average cycle length, then compare it with today. In irregular mode we compare against your longest cycle, so you are only called late when even your longest usual cycle has passed. The number of days shown is simply today minus that predicted date.
How it works
Enter your last period
Pick the first day of your most recent period — the day full bleeding started, not spotting.
Set your cycle length
Not sure? Use the built-in helper: enter a few past start dates and we compute your personal average.
Get instant answers
Next period date, ovulation day, fertile window and a 6-month forecast — plus a heads-up if you're running late.
Log it, and it gets personal
When your period actually starts, come back and tap "Log this period". After two or three logs we learn your real cycle length — not the textbook 28 days — and your predictions start using it.
Frequently asked questions
Is my period late?
If today is past your predicted start date, yes — and this page tells you by how many days. A few days off is normal variation; about a week or more past expected is the threshold most clinicians use for "late".
How many days late is concerning?
A one-off cycle a few days off is common. Around 7+ days late with a chance of pregnancy calls for a test. Three months without a period (pregnancy ruled out) should be evaluated by a clinician.
Can my period be late with a negative test?
Yes. Stress, weight change, exercise, illness, birth-control changes, PCOS and thyroid issues all delay ovulation — and a period follows ovulation, on its schedule, not yours. If tests stay negative and your period stays absent, see a clinician.
Can stress delay my period?
Yes. Stress hormones can postpone or suppress ovulation, which pushes the whole cycle back. A stressful month commonly shows up as a late period a few weeks later.
Am I pregnant if my period is late?
Pregnancy is one possible cause, not an automatic conclusion. A home test is usually reliable from about a week after your expected period. If negative and still absent after another week, test again or see a clinician.
When should I see a doctor about a late period?
If your period is absent for 3+ months, you have severe pain, very heavy bleeding when it arrives, fever, or new irregularity that persists for several cycles.