Luteal phase calculator
Our luteal phase calculator allows you to calculate the start and length of your luteal phase based on the ovulation date and the first day of your period
Your luteal phase cycle
- Updated Feb 25, 2025
- Published
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Created with Natasha Lowe Osho, MD, Obstetrician-Gynecologist, USA
The luteal phase is the second half of your menstrual cycle that starts after ovulation and typically lasts around 14 days until your next period—our calculator use this value as avarage. During this time, a fertilized egg can implant in the uterine lining, marking the beginning of pregnancy, which makes it crucial to track your luteal phase if trying to conceive. Our luteal phase calculator allows you to calculate the start and length of your luteal phase based on the ovulation date and the first day of your period.
What is the luteal phase?
The luteal phase begins right after ovulation and marks the second half of your menstrual cycle. This phase continues from ovulation until the next period. The average luteal phase length is around 12-14 days. Our calculator use 14 days value as average.
It’s also widely known as the “two-week wait” among trying-to-conceive (TTC) women. This is because the luteal phase is the time during which your recently released egg is either fertilized and implants into your uterine lining to start pregnancy or reabsorbed into your body if fertilization doesn’t happen.
Respectively, this phase plays a pivotal role in your menstrual cycle and reproductive system. Hence, answering the question “When is my luteal phase?” is important for tracking your cycle, understanding your fertility, and planning a pregnancy.
How to calculate the luteal phase
So, when is your luteal phase? In a 28-day menstrual cycle, the luteal phase begins on approximately the 14th day. However, since every woman and their cycles are different, the start and duration of this phase can vary from one woman to another, which indicates the need for personalized cycle tracking to understand your unique luteal phase better.
Luteal phase calculator
If you want to know “When is my luteal phase?,” another reliable and accurate tracking tool is a luteal phase calculator. Here’s how to calculate the luteal phase with our calculator:
- Enter the first day of your last period
- Enter the average length of your menstrual cycle
- Enter the average duration of menstruation
- Calculate
Just like this, our luteal phase calculator will help you understand the start and duration of your phase in a few clicks.
Rhythm method
The easiest way to monitor your luteal phase is by tracking your menstrual cycle—for example, with the rhythm method. This method requires counting the days of your cycle from one period to another to predict ovulation. You can also track your cycle with the help of fertility trackers and apps.
Symptom tracking
You can also predict the start of your luteal phase period by tracking physical symptoms, which may include:
- Breast tenderness and swelling
- Bloating
- Constipation or diarrhea
- Headache
- Swelling
- Appetite changes
However, keep in mind that the symptoms of the luteal phase can vary in timing and severity, which makes it hard to rely on physical symptoms alone in tracking your luteal phase. The most accurate way to tell when your luteal phase begins, based on symptoms, is by tracking your basal body temperature—it typically increases during ovulation, which can help you mark the beginning of your luteal phase.
It might also be helpful to keep an eye on your cervical mucus. During the luteal phase, it typically gets thicker and creamier to act as a barrier to keep sperm, bacteria, and infections from getting into your upper reproductive tract.
Ovulation kits
Over-the-counter ovulation kits are tests that react to increased levels of luteinizing hormone (LH) in the urine. These tests can help you track the start of ovulation and, hence, understand when your luteal phase starts.
Understanding luteal phase length
As you already know, in a 28-day menstrual cycle, the luteal phase typically starts on the 14th day. Respectively, the normal luteal phase length is around 14 days, though anywhere between 12–16 days is also considered normal.
Nevertheless, the start and duration of this menstrual cycle phase can vary greatly, and knowing how long is your luteal phase can help you understand deeper underlying causes and implications that you must be aware of:
- A short luteal phase is typically one that lasts for less than 10–12 days. It can be caused by lowered progesterone levels, hormonal imbalances, and stress and might lead to menstrual irregularity or reduced fertility in the long run.
- A long luteal phase lasts for 16 days or more. It can be caused by pregnancy, as your body continues producing higher levels of progesterone to sustain a pregnancy. However, it might also be a result of a polycystic ovary syndrome (PCOS) or luteal phase defect (LPD), which can lead to a number of implications.
Given the possible underlying health conditions and further implications caused by a shortened or prolonged luteal phase, it’s crucial for every woman to use a luteal phase calendar to be able to notice any abnormalities.
Luteal phase and implantation
During the luteal phase, your egg can still be fertilized within 12 to 24 hours after ovulation. After this, the egg travels down the fallopian tube and either implants, marking the start of pregnancy, or reabsorbs. Hence, this phase plays a crucial role in early pregnancy formation.
If you’re planning a pregnancy, using our implantation calculator with luteal phase calculations can help understand your implantation processes and gain peace of mind during the two-week wait. This calculator will help you predict when egg implantation can take place, when you may have implantation symptoms, and decide when it’s a good time to take a pregnancy test.
Questions from the Femia community
What if my luteal phase is shorter than 12 days?
While a 12-day luteal phase is typically considered normal, a luteal phase that’s shorter might signal underlying problems, such as an LPD or PCOS, which may affect your fertility. Thus, if you detect that the length of your luteal phase is too short, it’s important to consult with a healthcare provider for personalized advice and potential treatment options.
Can lifestyle changes affect my luteal phase?
Yes, your luteal phase period (as well as the overall menstrual cycle) can depend on various lifestyle factors, such as diet, exercise, stress, and overall health. Typically, it’s recommended to follow a balanced diet, regular physical activity, and a healthy lifestyle to regulate your luteal phase and general cycle.
How can I track my luteal phase without a calculator?
Common tracking options include tracking your menstrual cycle by counting the days from one period to the next. Tracking basal body temperature and other luteal phase symptoms can also help, as well as using fertility trackers and apps, such as the Femia fertility tracker.
The bottom line
The luteal phase begins after ovulation and plays a pivotal role in your reproductive processes. During this time, a fertilized egg can get implanted and begin a pregnancy, which is why understanding and tracking your luteal phase is important for understanding your cycle and planning pregnancy.
Don’t hesitate to use our ovulation calculator with luteal phase calculator and other available tracking methods to define the start and length of your luteal phase. And, don’t neglect seeking personalized medical advice if you notice any abnormalities or have other concerns about your menstrual cycle or fertility.
References
- “Luteal Phase.” Cleveland Clinic, 4, Nov. 2022. https://my.clevelandclinic.org/health/articles/24417-luteal-phase.
- “Rhythm Method.” Cleveland Clinic, 12, Aug. 2022. https://my.clevelandclinic.org/health/articles/17900-rhythm-method.
- Rachel Reiff Ellis, Zilpah Sheikh. “What Is the Luteal Phase?” Web MD, 8, May, 2024. https://www.webmd.com/women/luteal-phase.
- “Basal body temperature for natural family planning.” Mayo Clinic, 10, Feb. 2023. https://www.mayoclinic.org/tests-procedures/basal-body-temperature/about/pac-20393026#:~:text=Your%20basal%20body%20temperature%20is,predict%20when%20you%27ll%20ovulate.
- “Ovulation home test.” Medline Plus, 1, Apr. 2024. https://medlineplus.gov/ency/article/007062.htm#:~:text=The%20test%20detects%20a%20rise,an%20egg%20release%20is%20likely.
