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Cycle Length Calculation:
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Cycle length is the number of days between the first day of your period and the day before your next period starts. The average menstrual cycle is about 28 days, but normal cycles can range from 21 to 35 days.
The calculator uses this simple formula:
Where:
Explanation: The calculator first calculates the days between each consecutive period date you provide, then averages all those differences to determine your typical cycle length.
Details: Tracking your menstrual cycle can help identify irregularities, predict ovulation, and provide insights into overall reproductive health. Consistent tracking over several months provides the most accurate picture of your cycle.
Tips: Enter at least 2 period start dates (YYYY-MM-DD format), one per line. For best results, provide 3-6 months of data. The more dates you enter, the more accurate your average will be.
Q1: How many dates should I enter?
A: For a reliable average, enter at least 3-6 months of period start dates. The more data you provide, the more accurate your average cycle length will be.
Q2: What's considered a normal cycle length?
A: Normal cycles range from 21 to 35 days. The average is about 28 days. Consistently shorter or longer cycles may warrant medical consultation.
Q3: Why is my cycle length changing?
A: Cycle length can vary due to stress, diet, exercise, illness, or hormonal changes. Tracking helps identify patterns and irregularities.
Q4: How accurate is this calculator?
A: The calculator is only as accurate as the data you provide. More period dates yield more reliable averages.
Q5: Can I use this to predict my next period?
A: While it can estimate based on past cycles, many factors can affect timing. Use it as a guide rather than absolute prediction.