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Pregnancy calculators for dates that matter.
Due date, ovulation window and current week — estimated from the first day of your last period.
These three calculators use standard obstetric estimation methods — Naegele's rule for due dates, a luteal-phase estimate for ovulation — based on the first day of your last menstrual period and, where relevant, your typical cycle length. They're widely used starting estimates, not a diagnosis: actual due dates and ovulation timing vary by individual, and a healthcare provider using an ultrasound will give you a more precise picture.
Frequently asked questions
How is a due date calculated from the last period?
The most common method, Naegele's rule, adds 280 days (40 weeks) to the first day of your last menstrual period. It assumes a fairly typical 28-day cycle, so your provider may adjust the estimate based on an early ultrasound.
When am I most likely to be fertile?
Ovulation typically occurs about 14 days before your next period, and the fertile window — the days conception is most likely — generally spans the five days before ovulation through the day after it, reflecting sperm survival time and the egg's short viability window.
