Luteal phase calculator: how long is my luteal phase?
Luteal phase: 14 days
Within the typical range of 11 to 17 days.
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Your luteal phase runs from the day after ovulation to the day before your next period. Count the days from ovulation to the first day of your next period and that's its length. Most luteal phases last 11 to 17 days, often 12 to 14. You need a real ovulation date from LH tests or temperature charting; a calendar guess will just give you 14.
How to use the luteal phase calculator
- Enter the day you ovulated. Use the day after your first positive LH test, or the last low day before a sustained temperature rise on a basal body temperature chart.
- Enter the first day of the period that followed.
- Read your luteal phase length and whether it falls in the typical range.
If you estimate ovulation by counting 14 days back from your period, you'll always get 14 days. This calculator is for people who have tracked ovulation signs. Your dates stay in your browser.
What your result means
| Luteal phase | What it usually means |
|---|---|
| Under 10 days | Short. One short phase means little; if it keeps happening, mention it to a doctor |
| 11 to 17 days | Typical. Most people sit around 12 to 14 |
| Over 17 days | Check your dates. If your period is late, a pregnancy test is worth taking |
In a large app-based study, the average luteal phase was 12.4 days, and it varied far less than the follicular phase. That's why cycle length differences mostly come from the first half of the cycle. Still, the luteal phase can shift by a day or two from cycle to cycle, so look at a few before drawing conclusions.
Why the luteal phase matters
After ovulation, the empty follicle becomes the corpus luteum, which makes progesterone. Progesterone thickens and steadies the lining of the uterus so a fertilized egg can implant. If no pregnancy happens, the corpus luteum fades after about two weeks, progesterone and estrogen fall, and your period starts.
- For fertility: a very short luteal phase may leave less time for implantation. Doctors sometimes call this a luteal phase defect, though experts disagree about how much it matters on its own.
- For PMS: this is the phase where premenstrual symptoms live. The hormone drop at the end is when many people feel irritable, teary or anxious. See luteal phase mood.
- For your body: progesterone raises your resting temperature by about 0.2 to 0.5掳C, can make you hungrier and can disturb sleep in the last days.
What can shorten the luteal phase
Common reasons include the first cycles after coming off the pill, breastfeeding, intense training or under-eating, thyroid problems, high prolactin, PCOS and the years leading into perimenopause. Many are temporary. If you're trying to conceive and see several short luteal phases, it's worth raising with a doctor. More in short luteal phase.
Lulu marks your luteal phase in the calendar, can import Apple Watch wrist temperature through Apple Health for extra context, and learns from your check-ins which luteal days tend to be harder.
When to talk to a doctor
See a doctor if you repeatedly measure a luteal phase under 10 days and are trying to conceive, if you spot for several days before every period, or if you've been trying for 12 months (6 if you're 35 or older). Severe premenstrual mood symptoms are also worth raising.
Frequently asked questions
How long is a normal luteal phase?
Usually 11 to 17 days, most often 12 to 14. See how long is the luteal phase.
Can I calculate my luteal phase without tracking ovulation?
Not accurately. You need an ovulation date from LH tests, temperature or a scan. Counting back from your period just assumes 14.
Is a 10-day luteal phase too short?
It's at the short end. One cycle like that is common; a repeated pattern is worth discussing if you're trying to get pregnant.
Does the luteal phase change with age?
It can get shorter and less consistent in the years before menopause.
Sources
- Cleveland Clinic: Luteal phase
- Bull JR et al. Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles. npj Digital Medicine (2019)
- Cleveland Clinic: Ovulation
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
Luteal phase: why feelings get louderWhat the luteal phase is, how long it lasts, why progesterone rises and falls, and the common symptoms: PMS, cravings, low energy and mood changes.What is the luteal phase?What is the luteal phase? The part of your cycle from ovulation to your period, when progesterone rises and PMS happens. A plain explanation in 2 minutes.
Ovulation calculator: when do I ovulate?Free ovulation calculator: enter your last period and cycle length to see your likely ovulation day for the next 4 cycles. Private, instant, estimates only.
What is a short luteal phase, and does it matter?A short luteal phase is 10 days or fewer from ovulation to period. What causes it, what the research says about fertility, and when to see a doctor.
Luteal phase depression: why the second half of your cycle feels so heavyLuteal phase depression is low mood after ovulation that lifts with your period. What drives it, how it differs from PMDD and PME, and what helps.