Menstrual Cycle Phases: The 4 Stages Explained

The menstrual cycle has four phases: the menstrual phase (your period), the follicular phase, ovulation, and the luteal phase. Your cycle is counted from the first day of one period to the first day of the next, and hormones rising and falling drive the changes in each phase.

Quick summary: The four phases are menstrual, follicular, ovulation and luteal. Cycles are often around 28 days, but anywhere from about 21 to 35 days is common. The timing of each phase varies from person to person, and from cycle to cycle. Phases are a map, not a rulebook, so treat what you read here as tendencies.

The cycle at a glance

Your cycle is run by a conversation between your brain and your ovaries. The pituitary gland in the brain and the ovaries release hormones, including FSH (follicle-stimulating hormone), LH (luteinizing hormone), estrogen and progesterone. You can read more about them in our guide to estrogen, progesterone, LH and FSH across your cycle.

Here is the simple version:

Phase	Rough timing in a 28-day cycle	What is happening
Menstrual	Around days 1 to 5	The uterine lining sheds as your period
Follicular	From day 1 until ovulation	Follicles in the ovary grow, estrogen rises
Ovulation	Around day 14	An egg is released
Luteal	After ovulation until your next period	Progesterone rises, then falls if there is no pregnancy

The day numbers above are averages from a 28-day cycle. Many people have shorter or longer cycles, so your own timeline may look different. Our article on how long a normal cycle is goes into this.

Phase 1: Menstrual phase

This is the phase you can see. If pregnancy has not happened, estrogen and progesterone drop, and the lining of the uterus is shed as a period.

• The NHS says a period usually lasts about 5 days, though 2 to 7 days is a normal range.
• Bleeding is often heaviest in the first couple of days.
• Cleveland Clinic gives typical blood loss as about 2 to 3 tablespoons per period.

Many people notice cramps, tiredness or a lower mood at this time, but others feel fine. For ideas on what can help, see the menstrual phase: what's happening and what helps.

Phase 2: Follicular phase

The follicular phase starts on the first day of your period, so it overlaps with the menstrual phase. It ends at ovulation.

During this time, FSH nudges the ovaries to grow follicles, which are tiny fluid-filled sacs that each hold an immature egg. One follicle usually becomes dominant and keeps maturing. As it grows, it makes more estrogen, which helps rebuild the uterine lining.

Cleveland Clinic describes this phase as lasting around 10 to 14 days on average, and notes it can vary from cycle to cycle. Because it is the part that stretches or shrinks most, it is usually the reason one person's cycle is longer than another's.

Many people notice more energy, a better mood or clearer skin as estrogen climbs, but this is a tendency, not a promise. Read more in the follicular phase: energy, hormones and what to expect.

Phase 3: Ovulation

Ovulation is when an ovary releases a mature egg. A rise in estrogen triggers a surge of LH, and that surge prompts the egg to be released.

• Cleveland Clinic says the egg lives for about 12 to 24 hours after release.
• Sperm can live for several days in the reproductive tract, so the fertile window starts before ovulation itself.
• The NHS says ovulation happens about 12 to 16 days before your next period, and the Office on Women's Health notes the gap between ovulation and your next period can range from 7 to 19 days.

Signs can include clear, slippery cervical mucus, mild one-sided pelvic twinges, and a small rise in basal body temperature afterwards. Not everyone notices any signs at all.

Important: ovulation estimates are not birth control. Cycles can vary, and ovulation can shift from month to month. If you want to avoid pregnancy, talk to a doctor or sexual health clinic about methods that are proven to work. Learn more in the ovulatory phase and signs of ovulation.

Phase 4: Luteal phase

After ovulation, the empty follicle turns into a structure called the corpus luteum, which produces progesterone (and some estrogen). Progesterone thickens the uterine lining in case a fertilized egg implants.

Cleveland Clinic says the luteal phase is about 14 days in a 28-day cycle, and that 10 to 17 days is considered normal. If pregnancy does not happen, the corpus luteum breaks down, hormone levels fall, and your period begins.

This is also the phase when premenstrual symptoms show up. The NHS lists common ones, such as bloating, breast tenderness, mood changes, tiredness, headaches and changes in appetite. They usually ease within a few days of your period starting. Our guide to the luteal phase: symptoms, moods and cravings covers what may help.

Do the phases change how you should eat or train?

You may have seen "cycle syncing," which means changing your food, workouts or schedule to match your phase. Honest answer: the research is limited and early. A 2023 review from McMaster University reported little evidence behind phase-based advice and found hormone levels vary a lot between people and even between cycles in the same person. The researchers' takeaway was that there is no one-size-fits-all approach.

That does not mean you cannot pay attention to how you feel. Noticing that you are more tired before your period, or that you want rest on day one, is useful information about you. Just treat it as a personal pattern rather than a universal rule.

Why phases are not perfectly predictable

• 28 days is an average. Many people's cycles are shorter or longer.
• Stress, illness, travel, sleep changes and big lifestyle shifts can affect timing. See late period but not pregnant: common reasons.
• Age matters. Cycles can be irregular in the first few years after your first period and again approaching menopause.

If your cycles are often outside the 21 to 35 day range, see irregular periods: causes and when to see a doctor.

How to learn your own pattern

The best way to understand your phases is to log them for a few months: the first day of each period, how heavy it is, and any symptoms, moods or energy changes. We have a practical walkthrough in how to track your period and cycle.

When to talk to a doctor

Reach out to a doctor or nurse if you have:

• Severe pain that is stopping your usual activities
• Very heavy bleeding, such as soaking through a pad or tampon every 1 to 2 hours
• Periods lasting longer than 7 days
• No period for 3 months or more (and you are not pregnant)
• Bleeding between periods
• Symptoms that are affecting your daily life

Where Mochi Moon fits

Mochi Moon is an iPhone app launching in fall 2026 that lets you log your period, symptoms, moods, energy and sleep, and includes a phase guide that explains the four phases in plain language. Its predictions are estimates only, and the fertile window it shows is not birth control.