Comprehensive Calculator Guide
The luteal phase calculator splits your cycle into its two parts: the follicular phase from the first day of your period to ovulation, and the luteal phase from ovulation to the next period. In a 28-day cycle with ovulation on day 14, the luteal phase is 14 days. It tells you whether yours is in the usual range and when it’s worth asking a doctor.
What the luteal phase is
After ovulation the follicle becomes the corpus luteum, which makes progesterone to prepare the womb lining. Without pregnancy it fades after about two weeks and the period starts. The phase usually lasts 12–14 days; 10–17 is considered usual.
Under 10 days is called short and may not give the lining enough time. If it repeats while you’re trying to conceive, ask your doctor. Ovulation tests or temperature charting pin down the ovulation day better than calendar guesses.
How to Use
- Enter your usual cycle length in days.
- Enter the day of the cycle you ovulate, from an ovulation test or temperature chart.
- Press “Calculate” to see both phases and whether the luteal phase is usual.
Formula Used
Luteal phase = cycle length − ovulation day
Practical Examples
- Example 1
- 28-day cycle, ovulation day 14: luteal phase 14 days.
- Example 2
- 30-day cycle, ovulation day 20: luteal phase 10 days, at the low end.
Important Tips
- Track several cycles to learn your average.
Common Mistakes to Avoid
- Assuming ovulation is always on day 14.
Frequently Asked Questions
- How long is a normal luteal phase?
- Usually 12–14 days; 10–17 is in the usual range.
- How do I calculate it?
- Subtract the ovulation day from the cycle length.
- When does my period come after ovulation?
- After your luteal phase, about 12–14 days for most women.