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Menstrual cycle phases reference

Last updated October 10, 2026

General information, not medical advice. Cycles vary from person to person, so treat these as typical ranges. Talk to a healthcare professional about health concerns.

A typical 28-day cycle has four phases: menstrual (days 1 to 5), follicular (days 1 to 13), ovulatory (around day 14) and luteal (days 15 to 28).

At a glance

The follicular phase begins on day 1 and overlaps with menstruation until bleeding stops. It continues up to ovulation.

1. Menstrual phase

Typical timing: day 1 to day 5, overlapping with the early part of the follicular phase.

What's happening

Estrogen and progesterone are relatively low at the start of menstruation, because the corpus luteum from the previous cycle is no longer producing high levels of progesterone. The endometrium (uterine lining) sheds, which causes menstrual bleeding.

Pregnancy probability

Very low. Menstruation marks the start of a new cycle and ovulation is still roughly 10 to 14 days away. It is not zero, especially with a shorter cycle or because sperm can remain viable in the reproductive tract for several days.

Common mood and symptoms

• Mood: some people feel relief from premenstrual symptoms once bleeding begins, while others still have mood changes such as fatigue or irritability.
• Physical: cramping (dysmenorrhea), bloating, backaches, breast tenderness and headaches. Energy may be lower.

Tips

• Warm compresses or gentle heat can help relieve cramps.
• Staying hydrated and keeping up light to moderate exercise, such as yoga or walking, can improve mood and circulation.
• Iron-rich foods or supplements may help if you are prone to low iron from menstrual blood loss. Ask a healthcare provider for personal advice.

2. Follicular phase

Typical timing: day 1 to day 13.

What's happening

Follicle-stimulating hormone (FSH) from the pituitary gland stimulates ovarian follicles to develop, and estrogen begins to rise. Several follicles start to mature, but usually only one becomes dominant and is prepared for ovulation. The endometrium starts to thicken again under rising estrogen.

Pregnancy probability

Increasing but still moderate. The closer you get to ovulation, the higher the chance of pregnancy from unprotected intercourse. Sperm can survive up to about five days in fertile cervical mucus.

Common mood and symptoms

• Mood: as estrogen climbs, many people notice better mood, more energy and clearer thinking.
• Physical: a possible gradual rise in libido, and cervical fluid that is thinner and more elastic ("fertile mucus"). PMS-like symptoms are often fewer than in the luteal phase.

Tips

• This is often a good time for high-energy workouts and social activities.
• If you are trying to conceive, tracking cervical mucus or using ovulation predictor kits toward the end of this phase can help.

3. Ovulatory phase

Typical timing: around day 14 in a 28-day cycle.

What's happening

A surge in luteinizing hormone (LH) triggers the dominant follicle to release the mature egg. The egg moves into the fallopian tube, where it stays viable for about 12 to 24 hours.

Pregnancy probability

This is the peak fertility window. Sperm present in the reproductive tract up to about five days before ovulation, on the day, or shortly after can fertilize the egg.

Common mood and symptoms

• Mood: often more libido, energy and confidence, linked to peaking estrogen and testosterone.
• Physical: some people feel mild pelvic twinges (Mittelschmerz). Cervical mucus becomes clear and stretchy, like egg white, and basal body temperature may rise slightly after ovulation.

Tips

• If you are trying to conceive, intercourse in the days leading up to and including ovulation matters most.
• Staying hydrated and listening to your body can help with mild ovulatory discomfort.

4. Luteal phase

Typical timing: day 15 to day 28.

What's happening

After the egg is released, the follicle becomes the corpus luteum, which secretes progesterone and some estrogen. Progesterone prepares the uterus for a possible pregnancy, and the endometrium becomes thicker and more glandular.

Pregnancy probability

Higher early in the luteal phase, then decreasing. If fertilization and implantation occur, progesterone stays high (supported by hCG) to sustain the pregnancy. If not, progesterone drops and the uterine lining sheds as menstruation.

Common mood and symptoms

• Mood: PMS or PMDD symptoms can appear as progesterone and estrogen fall toward the end of the phase: irritability, low mood, anxiety and mood swings.
• Physical: bloating, breast tenderness, fatigue, food cravings, changes in bowel habits and fluid retention.

Tips

• Nutrient-dense foods, balanced meals and enough water can help steady mood and energy.
• Moderate exercise, mindfulness and stress reduction can ease PMS symptoms.
• Tracking symptoms helps you spot patterns and manage the changes.

Where RhythmX fits

RhythmX shows today's phase as a moon on the Insights ring (new, crescent, full or waning), tints the calendar by phase and keeps this same Phase Guide in the app. Everything stays on your iPhone. To see why that matters, read how to track your cycle privately.

General information, not medical advice. Talk to a healthcare professional about health concerns.