Average Cycle Length Calculator
Average your last few cycle lengths to predict the next one.
Your result
Normal cycles are 21–35 days. Variation of more than about 7–9 days between cycles is worth mentioning to a clinician.
Medical disclaimer: This tool is for education and is not medical advice. Read more.
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Frequently asked questions
What does the Average Cycle Length Calculator do?
Average your last few cycle lengths to predict the next one. Enter your values and the result and chart update instantly.
How accurate is it?
It uses published, widely used formulas. Results are estimates for education and planning, not a diagnosis. Talk to a qualified clinician about decisions affecting your health.
Is my information stored or shared?
No. All calculations run in your browser and nothing you type is sent to a server or saved.
What can I search to find this tool?
People find it by searching for: average menstrual cycle length; typical cycle length; how long is my cycle.