The four phases of the menstrual cycle, explained
A menstrual cycle is not one event with three quiet weeks around it. It is a continuous loop of four phases, each with its own hormone pattern, and each with a recognisable set of physical and emotional effects.
Once you can name the phase you are in, a great deal of the month stops feeling random. This page walks through all four in order, with the typical lengths and the things people most often notice.
The cycle at a glance
Day 1 of your cycle is the first day of proper bleeding, not spotting. The cycle ends the day before your next period starts. A cycle anywhere from roughly 21 to 35 days is considered within the usual range for adults, and cycles are often longer and less regular in the first years after periods begin and in the years approaching menopause.
| Phase | Typical days | What's happening | Commonly noticed |
|---|---|---|---|
| Menstrual | Day 1–5 | The uterine lining sheds; oestrogen and progesterone are at their lowest. | Bleeding, cramps, tiredness, lower back ache, wanting warmth and quiet. |
| Follicular | Day 1–13 | Follicles develop in the ovaries and oestrogen climbs. | Energy and mood lifting, clearer skin, more sociable, stronger in training. |
| Ovulation | Around day 14 | An egg is released; oestrogen peaks and luteinising hormone surges. | Clear stretchy discharge, a small temperature rise afterwards, sometimes one-sided twinges. |
| Luteal | Day 15–28 | Progesterone rises then falls if there is no pregnancy. | Breast tenderness, bloating, appetite changes, mood dips, disturbed sleep in the last days. |
Phase one: menstrual
The bleed itself is the start of the cycle, not the end of it. The lining built up over the previous month is shed, prostaglandins make the uterus contract, and those contractions are what most cramping is.
Most bleeds last between two and seven days, and are heaviest in the first two. Tiredness in this phase is normal and worth planning around rather than pushing through: this is the week to move meetings that can move, and to make warmth easy to reach.
Phase two: follicular
The follicular phase overlaps with your period — it begins on day 1 too — but it is defined by what happens after the bleed. Oestrogen rises steadily, the lining rebuilds, and most people feel it: more energy, better mood, more appetite for plans and hard training.
If you are going to schedule anything demanding, this is usually the most forgiving stretch of the month.
Phase three: ovulation
Ovulation is a moment rather than a week: a surge in luteinising hormone releases an egg, typically around the middle of the cycle but genuinely variable from person to person and month to month.
The most reliable everyday signs are cervical mucus that becomes clear and stretchy, like raw egg white, and a small sustained rise in resting body temperature in the days afterwards. Some people feel a brief one-sided ache.
Phase four: luteal
After ovulation the empty follicle becomes the corpus luteum and produces progesterone, which keeps the lining in place in case of pregnancy. Progesterone is calming for some people and flattening for others.
If there is no pregnancy, the corpus luteum breaks down and both hormones drop sharply. That drop is the trigger for both the bleed and most of what people call PMS — which is why the last three or four days of the cycle so often feel like the hardest.
Why the phases are worth knowing
It makes symptoms legible
A mood dip on day 25 stops being a personality flaw and starts being a hormone withdrawal you can plan around.
It changes what helps
Heat and rest do more in the menstrual phase; sleep, magnesium-rich food and lighter training tend to do more in the late luteal phase.
It tells you what is unusual
You can only spot a change worth mentioning to a GP — a cycle that suddenly shortens, a bleed that suddenly doubles — if you know your own pattern.
When to speak to a GP
See a GP if your cycle suddenly changes length, your bleeding is heavy enough to soak through protection hourly or lasts more than seven days, you bleed between periods or after sex, or pain stops you doing normal activities. None of that is something to wait out.
This page is general information about menstrual health, not personal medical advice. For urgent concerns contact your GP or NHS 111.
Where Surreal Comfort fits
Knowing your phases makes restocking predictable, which is the whole idea behind a monthly box: protection and comfort arrive before the bleed rather than during it.
The four phases — frequently asked
What are the four phases of the menstrual cycle?
The four phases are the menstrual phase (the bleed), the follicular phase (the lining rebuilds as oestrogen rises), ovulation (an egg is released), and the luteal phase (progesterone rises, then falls if there is no pregnancy).
How long is each phase of the menstrual cycle?
In a 28-day cycle the menstrual phase is usually two to seven days, the follicular phase runs from day 1 to around day 13, ovulation happens around day 14, and the luteal phase runs from ovulation to the day before the next period — usually 11 to 17 days.
Which day of the cycle is day 1?
Day 1 is the first day of full bleeding, not the first day of spotting. Counting from the wrong day is the single most common reason a cycle looks irregular when it is not.
Is a 28-day cycle normal?
It is a common average rather than a standard. Adult cycles anywhere from roughly 21 to 35 days are considered within the usual range, and some variation month to month is expected.
Can the phases change length?
Yes. The follicular phase is the most variable and is usually what makes a cycle longer or shorter overall. The luteal phase tends to be more consistent for an individual, so a noticeable change there is worth mentioning to a GP.