Pregnancy due date calculator.
Estimate a due date and gestational age from the last menstrual period.
Estimate your timeline
Dates are estimates. Irregular cycles, recent hormonal contraception and uncertain period dates reduce reliability.
Estimated from the first day of the last menstrual period, adjusted for cycle length. Gestational age shown is unadjusted LMP age. Ultrasound and clinical review may establish a different due date.
How this pregnancy due date calculator works
Conventional pregnancy dating starts on the first day of the last menstrual period. A 28-day cycle gives a due date 280 days later. This calculator shifts that date by the difference between your cycle length and 28 days, while showing unadjusted LMP gestational age separately.
A worked example
For a last period beginning 1 August 2026 and a 28-day cycle, the estimate is 8 May 2027. On 12 September 2026, LMP gestational age is 6 weeks.
Can this replace the due date from an ultrasound?
No. Clinical history and ultrasound can establish or revise dating. An estimated due date is not a prediction of the exact delivery day, especially when cycles or period dates are uncertain.
References and further reading
Calculations run on your device. Review your results before exporting or sharing them.