Understanding your cycle
Your cycle moves through four phases each month. Knowing what each one does helps explain how you feel.
The four phases
- Period (days 1–5): the lining of your uterus comes out as bleeding. Tiredness, cramps, and low mood are common.
- Build-up phase (days 1–13): your body's estrogen level goes up. Energy and mood usually lift, and your body gets ready to release an egg.
- Ovulation (around day 14): an ovary releases an egg. Some people feel more energetic or notice a higher sex drive.
- Pre-period phase (days 15–28): another hormone called progesterone goes up. You may feel calmer at first, then notice PMS (mood changes, cravings, or tender breasts) closer to your next period.
Cycle length naturally ranges from 21 to 35 days. Track yours for a few months to see your own pattern - everyone's is a little different.
Common questions
Quick answers to questions people often have about this topic.
How long is a "normal" cycle?
Anywhere from 21 to 35 days is considered typical for adults. What matters more than the exact number is whether your own cycle is roughly steady from month to month.
Is it normal for my cycle length to change?
Yes, small differences from month to month are normal. Stress, illness, travel, sleep changes, and intense exercise can all shift things by a few days.
When in my cycle am I most likely to get pregnant?
In the few days leading up to ovulation and the day of ovulation itself - usually around the middle of your cycle. See the guide on fertile days for the signs to watch for.
Why do I feel different at different times of the month?
Hormone levels rise and fall through your cycle, which can affect energy, mood, sleep, appetite, and skin. Logging how you feel each day helps you spot your own pattern.