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Your fertile window,
calculated for you.

Most ovulation calculators assume a perfect 28-day cycle. Luna calculates your fertile window from your actual cycle history — including irregular cycles — so you know your real chances of conceiving.

Calculate my ovulation →
🔒 Data stays on your device 🌡️ Basal temperature support 🌍 11 languages

How the calculator works

Enter your recent period datesThe more cycles you log, the more accurate the prediction.
Luna finds your patternIt calculates your average cycle length instead of assuming 28 days for everyone.
See your fertile windowGet your estimated ovulation day, high-fertility days, and next period date.
Confirm with temperatureLog your basal body temperature each morning to confirm ovulation actually happened.

Built for real cycles, not average ones

Irregular cycles supportedNo fixed assumptions — the calculator adapts as your history grows.
Conception day trackingLog the days you tried, and see which ones actually fell in your fertile window.
Ovulation confirmationBasal temperature charting flags the post-ovulation rise automatically.
Full fertility calendarNot just one date — a month-by-month view of fertile days, ovulation, and period predictions.