Pink Mom MathLuteal Phase Calculator
Enter your ovulation date and next period start date to calculate your luteal phase length and see how it compares to the normal 12–16 day range.
How the Luteal Phase Calculator Works
The luteal phase length is calculated as the number of days between your ovulation date and the first day of your next period:
Luteal Phase Length = differenceInDays(Next Period Date, Ovulation Date)
What the Result Means
- 12–16 days (Normal): Your luteal phase is within the healthy range. Progesterone levels are likely sufficient to support early pregnancy.
- Fewer than 12 days (Short): May indicate luteal phase deficiency. The uterine lining may not have enough time to prepare for implantation.
- More than 16 days (Long): Usually not a concern, but a consistently long luteal phase may warrant evaluation if you are experiencing pregnancy symptoms.
Frequently Asked Questions
Related Calculators
Cycle Length Analyzer
Analyze your cycle consistency with a 0–100 regularity score and detect irregularities from your period history.
Ovulation Calculator
Calculate your ovulation day and fertile window based on your cycle. Supports irregular cycles and PCOS mode.
BBT Ovulation Calculator
Detect ovulation from daily basal body temperature readings with a visual temperature chart and coverline.
Period Prediction Calculator
Predict your next 6 months of period dates based on your cycle history with a scrollable calendar.
Related Guides
What Your Cycle Length Tells You About Your Health
A guide to interpreting your menstrual cycle length — what is normal, what signals irregularity, and how cycle patterns reflect hormonal and overall health.
Understanding Your Luteal Phase
What the luteal phase is, why its length matters for fertility and PMS, what a short luteal phase means, and how to optimize it for better cycle health.
This calculator provides estimates for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider with questions about your health or your baby's health.
Based on standard luteal phase physiology. Normal range: 12–16 days. If you have concerns about your luteal phase, consult your healthcare provider.