Free Period Tracker
Predict your next period, ovulation date, and fertile window — free, private, nothing stored.
Answer three easy questions and get a customized period tracker!
Disclaimer: This tool provides estimated dates and should not be used for medical purposes. Cycle length and ovulation can vary. Please consult a healthcare provider for personal advice.
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How to Use This Period Tracker
Using this period tracker takes less than a minute:
- Enter the first day of your last period
- Enter how many days your period lasted
- Enter your average cycle length (most women are 28–32 days)
- Click Track Now
The calculator shows your predicted next period dates, ovulation
day, and fertile window for the next 3 months — all in a
visual calendar.
Your data stays in your browser. Nothing is saved or sent anywhere.
When Is My Next Period?
Your next period date is calculated by adding your cycle length to the first day of your last period. For example, if your last period started on March 1 and your cycle is 28 days, your next period is expected around March 29.
Most women have cycles between 21 and 35 days. A 28-day cycle is the average, but shorter or longer cycles are completely normal.
Use the tracker above to get your predicted dates for the next 3 months at once.
How to Calculate Your Ovulation and Fertile Window
Ovulation typically happens about 14 days before your next period starts — not 14 days after your last period.
For a 28-day cycle: ovulation falls around day 14.
For a 30-day cycle: ovulation falls around day 16.
For a 35-day cycle: ovulation falls around day 21.
Your fertile window is the 6-day window that includes:
| Day | What Happens |
|---|---|
| Day -5 to -2 | Sperm can survive and wait for egg |
| Day -1 | Most fertile — day before ovulation |
| Ovulation Day | Egg released — peak fertility |
| Day +1 | Fertility drops sharply |
If you are trying to conceive, these are your best days.
If you are avoiding pregnancy, note that this window can shift if your cycle is irregular.
Understanding Safe Days and Your Menstrual Cycle Phases
Your menstrual cycle has four phases:
| Phase | Days (28-day cycle) | What Happens |
|---|---|---|
| Menstruation | Day 1–5 | Period bleeding |
| Follicular | Day 1–13 | Estrogen rises, egg develops |
| Ovulation | Day 14 | Egg released |
| Luteal | Day 15–28 | Progesterone rises, PMS possible |
“Safe days” — the period is generally less fertile — are typically the days just after your period ends and the days after ovulation until your next period. However, cycle length varies month to month, which makes safe days unreliable as a sole contraception method.
For family planning decisions, consult a healthcare provider.
Why Is My Period Late?
A period is considered late if it hasn’t started within 5 days
of your expected date. Common reasons include:
- Stress — cortisol can disrupt hormone levels and delay ovulation
- Significant weight loss or gain
- Excessive exercise
- Thyroid issues
- Polycystic Ovary Syndrome (PCOS)
- Pregnancy
- Perimenopause (women over 40)
A single late period is usually not a concern. If your period is consistently irregular or missing for more than 3 months, consult a doctor to rule out underlying causes.