Fertility, ovulation, conception, and implantation calculators.
5 calculators
Pregnancy dating, gestational age, weight, and nutrition calculators.
7 calculators
Period prediction, menstrual cycle, cycle phases, and menstrual health calculators.
6 calculators
Body composition, sizing, nutrition, and women's health tools.
7 calculators
Free tools for planning — with clear limits on what they can and cannot tell you.
These calculators use standard clinical dating methods (LMP-based, luteal-phase, and ultrasound-based estimates) and are intended for general planning purposes. They are not a substitute for medical advice — consult a healthcare provider for guidance specific to your situation.
Methodology: Estimates follow widely used clinical dating conventions (including 280-day LMP pregnancy dating and typical luteal-phase timing for ovulation windows), consistent with guidance from ACOG and NIH pregnancy-dating resources. When ultrasound or your clinician revises dates, use that input instead of calendar estimates alone.
Ovulation accuracy, due-date math, privacy, and when to see a clinician.
Online ovulation calculators estimate your fertile window using average cycle length and standard luteal-phase timing (ovulation typically occurs about 14 days before your next period). They're a reliable starting estimate for most regular cycles, but actual ovulation timing can vary — tracking methods like basal body temperature or ovulation tests give more precise, individual confirmation.
The most common method adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). If you know your conception date or had an early ultrasound, those methods can give a more precise estimate, especially for irregular cycles.
No — these are dating and planning calculators, not diagnostic tools. They estimate fertile windows, due dates, and cycle timing based on the dates you enter. A pregnancy test or a healthcare provider is the only way to confirm pregnancy.
No. All calculations run in your browser and nothing you enter is stored, saved, or sent anywhere. You can use every calculator without creating an account.
An ovulation calculator estimates your fertile window before conception, based on your cycle. A due date calculator works after conception — or after a missed period — to estimate when a pregnancy is likely to reach full term.
They're less precise for irregular cycles, since the underlying formulas assume a fairly consistent cycle length. If your cycles vary significantly, an ultrasound-based due date estimate or a fertility specialist's assessment will be more accurate than a calendar-based calculator alone.