What phase of my cycle am I in?
Your phase depends on your cycle day and on how long your cycles usually run. Your cycle day counts from the first day of your last period. Put that date and your cycle length in the calculator above.
How to work out your cycle phase by hand
Say your last period started on September 1. Your cycles run 30 days and you bleed for 5. Here’s how to find your phase on September 20.
- Count the cycle day. September 1 is day 1, so September 20 is day 20.
- Find your next period. September 1 plus 30 days is October 1.
- Count back 14 days from that period to estimate ovulation. That gives September 17, which is day 17.
- Read off the phase. Days 1 to 5 are your period. Days 6 to 15 are follicular. The ovulation phase is day 17 and the day before it. Every day after day 17 is luteal, and that includes day 20.
Count back 14 days if your cycle is 25 to 32 days long. Count back 12 for a shorter cycle and 15 for a longer one. Plum and this calculator both use that rule.
The four phases of the menstrual cycle
Here’s how a 28-day cycle with a 5-day period splits up.
- The menstrual phase is your period. It covers days 1 to 5.
- The follicular phase runs from the end of your period to ovulation. It covers days 6 to 13. Cleveland Clinic describes it as the time when your ovaries prepare eggs for ovulation.
- Ovulation covers days 14 and 15. Your next period is due on day 29, and counting back 14 days from it lands on day 15. That’s the estimated ovulation day, and the phase includes the day before it. Cleveland Clinic puts ovulation at about day 14 of a 28-day cycle, so the two are a day apart. These dates are estimates from a calendar. They aren’t contraception, and they can’t tell you a day when pregnancy is impossible.
- The luteal phase runs from after ovulation to your next period. It covers days 16 to 28.
Doctors draw one line differently. In medical terms the follicular phase starts on day 1, so it overlaps your period. Plum’s in-app phase notes say the same. Plum’s home screen and this calculator still show the menstrual phase while you bleed, and they start the follicular phase the day after.
How the phases move with cycle length
The time from ovulation to your next period barely changes, so the follicular phase takes up the difference. A longer cycle usually means a longer follicular phase and a later ovulation. Here are the phases by cycle length, each with a 5-day period.
| Cycle length | Menstrual phase | Follicular phase | Ovulation | Luteal phase |
|---|---|---|---|---|
| 22 days | Days 1 to 5 | Days 6 to 9 | Days 10 to 11 | Days 12 to 22 |
| 28 days | Days 1 to 5 | Days 6 to 13 | Days 14 to 15 | Days 16 to 28 |
| 30 days | Days 1 to 5 | Days 6 to 15 | Days 16 to 17 | Days 18 to 30 |
| 32 days | Days 1 to 5 | Days 6 to 17 | Days 18 to 19 | Days 20 to 32 |
| 35 days | Days 1 to 5 | Days 6 to 19 | Days 20 to 21 | Days 22 to 35 |
| 38 days | Days 1 to 5 | Days 6 to 22 | Days 23 to 24 | Days 25 to 38 |
What phase am I in on day 17 or day 18?
In a 28-day cycle, day 17 and day 18 are in the luteal phase. In a 35-day cycle they’re still follicular, because ovulation comes later. The table below is for a 28-day cycle with a 5-day period. If yours runs longer or shorter, use the calculator instead.
| Cycle day | Phase | Next period due in |
|---|---|---|
| Day 1 | Menstrual phase | 28 days |
| Day 2 | Menstrual phase | 27 days |
| Day 3 | Menstrual phase | 26 days |
| Day 4 | Menstrual phase | 25 days |
| Day 5 | Menstrual phase | 24 days |
| Day 6 | Follicular phase | 23 days |
| Day 7 | Follicular phase | 22 days |
| Day 8 | Follicular phase | 21 days |
| Day 9 | Follicular phase | 20 days |
| Day 10 | Follicular phase | 19 days |
| Day 11 | Follicular phase | 18 days |
| Day 12 | Follicular phase | 17 days |
| Day 13 | Follicular phase | 16 days |
| Day 14 | Ovulation | 15 days |
| Day 15 | Ovulation | 14 days |
| Day 16 | Luteal phase | 13 days |
| Day 17 | Luteal phase | 12 days |
| Day 18 | Luteal phase | 11 days |
| Day 19 | Luteal phase | 10 days |
| Day 20 | Luteal phase | 9 days |
| Day 21 | Luteal phase | 8 days |
| Day 22 | Luteal phase | 7 days |
| Day 23 | Luteal phase | 6 days |
| Day 24 | Luteal phase | 5 days |
| Day 25 | Luteal phase | 4 days |
| Day 26 | Luteal phase | 3 days |
| Day 27 | Luteal phase | 2 days |
| Day 28 | Luteal phase | 1 day |
Which phase am I in after my period, or a week before it?
- Right after your period, you’re in the follicular phase. It lasts until ovulation. In a 28-day cycle that’s about a week.
- In a 28-day cycle, two weeks after your period started, you’re at ovulation. That’s day 15.
- In a 28-day cycle, two weeks after your period ended, you’re in the luteal phase. With a 5-day period that’s day 19.
- A week before your period, you’re in the luteal phase. In this calculator that holds for any cycle length, because the luteal phase always covers at least the last 11 days before a period.
Is there a luteal phase calculator?
The luteal row in the calculator above is one. Cleveland Clinic says the luteal phase lasts about 14 days. If you use ovulation tests and know your own ovulation day, count the days from it to your next period. That number is your own luteal length.
What changes on hormonal birth control?
Combined pills, the patch and the ring work mainly by stopping ovulation. Without ovulation there’s no follicular or luteal phase in the usual sense. The bleed in your break week is a withdrawal bleed caused by the drop in hormones. So the phases on this page describe a cycle you aren’t having. Our guide to tracking your period on birth control covers each method.
Plum asks about birth control when you set it up. On a hormonal method it hides ovulation and the fertile window on the calendar by default, and it doesn’t send the ovulation reminder. The home screen still counts cycle days from the last bleed you logged. On a hormonal method, read its phase as a count of days.
Is there a period tracker that tells you what phase you’re in?
Yes. Plum, a period tracker app for iPhone, shows your cycle day and phase on its home screen. It uses the same rule as this calculator, with the periods you log in place of the numbers you typed here. Tap the phase to read what usually happens in it. None of that costs anything.
Plum also picks tips for the part of your cycle you’re in, such as your period or the days just before it. You can see the tip cards for free. Opening a full tip needs Plum Premium.
