Free Period & Fertility Calculators
Track your cycle, predict ovulation, and understand your body better. All tools are free, private, and work right in your browser.
Track your cycle, predict ovulation, and understand your body better. All tools are free, private, and work right in your browser.
Estimate your implantation date and earliest pregnancy test window in seconds.
Estimate ovulation and your fertile window after miscarriage using your first real period date and average cycle length.
Find out which phase of your menstrual cycle you're in right now.
Predict your next period and menstrual cycle dates in seconds.
Calculate your average period cycle length using your last few periods.
Predict your next period date and understand your menstrual cycle in seconds.
Predict your next period date with pinpoint accuracy, based on your actual cycle length.
Find out exactly how many calories you need each day during pregnancy.
Calculate your safe days and unsafe days based on your menstrual cycle.
Find your exact ovulation day and peak fertility window based on your cycle data.
Calculate your monthly period cycle and predict your next period date in seconds.
Estimate your next period and fertile window, even with irregular cycles.
See your follicular phase dates, symptoms, and what to eat for optimal energy.
See exactly which phase you're in today and what's coming next.
See your fertile window and peak days to get pregnant.
Find your ovulation date and 6-day fertile window in seconds.
Calculate your next period date in seconds. Enter your last menstrual period start date, hit calculate, done.
Each tool uses the same science doctors rely on — the only difference is you get results instantly, without an appointment. Our period calculator predicts your next cycle, the ovulation calculator finds your fertile window, and the fertility calculator shows when conception is most likely.
No signup required, no data stored on servers, completely free. Whether you're planning a pregnancy, managing symptoms, or just staying organized.
Your cycle has four phases: the follicular phase prepares an egg for release, ovulation is your fertile window, the luteal phase is when PMS may appear, and menstruation starts the cycle over. The average is 28 days, but 21–35 is normal.
Tracking helps you spot patterns, plan ahead, and catch irregularities early. Our period calculator and ovulation calculator give you the data you need.
Simple, private, accurate, and always free.
All calculations happen in your browser. Nothing stored, nothing shared.
Based on the same cycle science healthcare providers use.
No signup, no waiting. Enter your dates and get results in seconds.
Yes, completely free. No subscriptions, no trial periods, no credit card required.
Your data never leaves your device. All calculations happen locally in your browser — we don't collect or store anything.
For regular cycles, predictions are typically accurate within 1-3 days. Accuracy depends on how consistent your cycles are.
No. Just visit the calculator, enter your dates, and get results instantly.
A period calculator predicts when your next period will start. An ovulation calculator identifies when you're most likely to be fertile — usually about 14 days before your next period.
Cycle predictions, reminders, and history — all free, all private.
Try Full Period Tracker