How do you figure out the length of your cycle?
Matthew Harrington
Updated on January 30, 2026
The length of your menstrual cycle is the number of days from the first day of bleeding in your last period, to the first day of bleeding in your next. From this figure, subtract 14 days from the end of your current cycle to determine the approximate day you ovulate.
What is a normal cycle length?
The length of the menstrual cycle varies from woman to woman, but the average is to have periods every 28 days. Regular cycles that are longer or shorter than this, from 21 to 40 days, are normal.
What does the length of your menstrual cycle mean?
The length of your cycle is the number of days between periods, counting the first day of your period until the day before your next period starts. For adults not using any form of hormonal contraception, a typical cycle length ranges between 24 to 38 days.
What is considered day 1 of period?
Day 1 of your cycle is the first day of your period, meaning the first day of full flow (spotting doesn’t count). During this time, the uterus sheds its lining from the previous cycle. Between days 1 – 5 of your cycle, new follicles (sacs of fluid containing eggs) begin to develop within your ovaries.
Is a 38 day cycle Normal?
These changing hormone levels can cause menstrual symptoms. Menstrual cycles often change as a woman gets older. A normal cycle lasts between 24 and 38 days.
When do you ovulate with a 40 day cycle?
Women with regular cycles consistently have periods every 21 to 35 days. If you have a 28-day cycle, your ovary likely releases an egg 14 days after the first day of your last period, although the timing can vary. If your cycles last 35 days or longer, you probably ovulate at day 21 or later.
What causes menstrual cycle to change dates every month?
During your lifetime, your menstrual cycle and periods change and evolve due to normal age-related hormonal changes and other factors such as stress, lifestyle, medications and certain medical conditions.
Do periods get shorter with age?
Menstrual flow might occur every 21 to 35 days and last two to seven days. For the first few years after menstruation begins, long cycles are common. However, menstrual cycles tend to shorten and become more regular as you age.
Do periods start in the morning or night?
A significantly greater number of cycles (70.4%) commenced during the night or in the first 4 h after rising, compared with later in the day. In a large proportion of these (29 out of 76), blood was noted to be present on waking, menstruation thus having begun at some time during the hours of sleep.
Does get your period at night count as Day 1?
Menstruation: Days 1 – 5 Day 1 of your cycle is the first day of your period, meaning the first day of full flow (spotting doesn’t count). During this time, the uterus sheds its lining from the previous cycle.
How can I find out how long my cycle is?
To figure out how long your cycle is, start at cycle day 1 of your last menstrual cycle and begin counting (Cycle day 1,2,3,4 and so forth).
How to calculate the length of your menstrual cycle?
Ex.= February 2nd. To figure out how long your cycle is, start at cycle day 1 of your last menstrual cycle and begin counting (Cycle day 1,2,3,4 and so forth). The length= the last cycle day before you started bleeding again.
When does your menstrual cycle start and end?
Your cycle begins on the first day you have regular bleeding. Spotting doesn’t count. For example, Cycle Day 1 is the first day of your period; Cycle Day 2 is the second day of your period, Cycle Day 3 is the third day of your menstrual flow, and so forth. As an example, create sample menstrual calendar for the month of January.
When do you start counting the days of your period?
Mark the first day of your period on the calendar. The first day of your period is Day 1 of your menstrual cycle. Starting on the first day of your period, start counting. The day before your next period is the last day of your menstrual cycle. That’s when you stop counting.