Free Online Period Calculator — Track Your Menstrual Cycle
Predict your next period and track your cycle. Based on standard 28-day model with adjustable cycle length.
How Does a Period Calculator Work?
A period calculator uses the date of your last menstrual period (LMP) and your average cycle length to predict future periods. The calculation is simple: add your cycle length (typically 28 days) to the first day of your last period. Regular tracking over 3-6 months provides the most reliable predictions. The standard medical model assumes ovulation occurs 14 days before the next period.
Why Track Your Cycle?
Understanding your menstrual cycle helps with family planning, identifies irregularities that warrant medical attention, and helps you prepare for symptoms. Regular cycles (21-35 days) generally indicate good reproductive health.
Frequently Asked Questions
How accurate is the period calculator?
The calculator provides estimates based on your average cycle length. For most women with regular cycles, predictions are accurate within 1-2 days. Irregular cycles require tracking over several months for reliable patterns.
Can I use this if my cycle is irregular?
Yes. Enter your best estimate of average cycle length based on recent months. For more accurate tracking with irregular cycles, use our Cycle Analyzer tool to identify your personal pattern.
Does this work for birth control?
No. The period calculator is for tracking and educational purposes only. It should NOT be used as a contraceptive method. Consult a healthcare provider for birth control options.