The average length of a menstrual cycle is 28 days. Women, however, may experience cycles ranging from 21 to 35 days, and young teens may have cycles that range from 21 to 45 days. Since menstrual cycles can vary in length from month to month, you can track your cycles for a few months and use the lengths to calculate the duration of your average menstrual cycle. A menstrual cycle starts on the first day of your period and ends the day before your next period. The first day of your next period will start your next menstrual cycle. Calculating and averaging a menstrual cycle is simple.
Calculating a Menstrual Cycle
Step 1
Write "Cycle Day 1" on the date you start your period. This is the first day of your menstrual cycle.
Step 2
Write "End of Cycle" on the date before your next period.
Step 3
Add the number of days from "Cycle Day 1" to "End of Cycle." The number you calculate equals the length of your menstrual cycle.
Averaging the Menstrual Cycle
Step 1
Track the length of your menstrual cycles for at least three cycles.
Step 2
Add the length of each cycle together.
Step 3
Divide the number by "3" to determine your average menstrual cycle length.
Things You'll Need
- Calendar
References
- "Introduction to Maternity & Pediatric Nursing: Fourth Edition;" Gloria Leifer, M.A., R.N.; 2002
- National Women's Health Information Center
- Merck
