Free Online Pregnancy Due Date Calculator

1. Pick the calculation method: LMP, conception or ultrasound.
2. Enter the relevant date (and for ultrasound, the gestational weeks and days the scan reported).
3. Read the estimated due date, current gestational age and trimester.
4. Note that this is an estimate — most babies arrive within ±2 weeks of the predicted date.

Naegele's rule, the standard estimator for due dates, adds 280 days (40 weeks) to the first day of the last menstrual period. From a known conception date the figure is 266 days. From an ultrasound, the scan gives a current gestational age in weeks-and-days, and the remainder of the 280-day budget projects forward to the estimated date of delivery.

Expectant parents use it to plan parental leave, hospital bag deadlines and nursery-prep timelines. About 5% of babies actually arrive on the predicted day — most arrive within a two-week window either side, and first-trimester ultrasound dating is the most accurate predictor. This calculator returns the estimate, your current gestational age in weeks-and-days, the trimester (1: 0–13 weeks, 2: 14–27, 3: 28+) and how long is left until the estimated date.

This is general information only, not medical advice — pregnancy care decisions should be guided by a qualified obstetrician, midwife or family doctor. Verify dating at your booking appointment.