Period Calculator
Predict your next periodRuns locally · nothing uploaded
Estimates based on general formulas, for information only. Not a substitute for professional medical advice, diagnosis or treatment.
Predictions use your average cycle and are less accurate for irregular cycles. Talk to a doctor about late, missed or unusual periods.
Also works as:period trackernext period calculatormenstrual cycle calculator
How to use
- 1Choose the first day of your last period and enter your average cycle.
- 2Optionally add previous start dates to average your cycle.
- 3See your next period, cycle phase and the next six periods.
FAQ
What is a normal cycle length?
Typically 21–35 days, with bleeding lasting 2–7 days. Small variations are common.
When is a late period a concern?
If it's more than 7 days late and pregnancy is possible, take a test; see a doctor about ongoing irregularity.
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