Enter the first day of your last menstrual period (LMP) to estimate your due date and current pregnancy timeline.
You only need one date.
The estimated due date is calculated by adding exactly 280 calendar days to the first day of the last menstrual period. This is a standard LMP-based estimate.
This conventional LMP-based estimate assumes a typical 28-day menstrual cycle with ovulation around day 14. Irregular cycles, an uncertain LMP or different ovulation timing can make the estimate less reliable.
Gestational age is shown as completed weeks and remaining days counted from the first day of the LMP. For example, 14 weeks and 3 days means 14 full weeks plus 3 days.
The first trimester runs through 13 weeks 6 days, the second from 14 weeks through 27 weeks 6 days, and the third begins at 28 weeks.
LMP dating may differ when the date is uncertain or menstrual cycles are irregular. A clinician may confirm or revise the estimate using clinical information and ultrasound.
This calculator adds 280 days to the first day of the last menstrual period. It is intended for general information and does not provide medical advice, confirm pregnancy, or assess pregnancy health. LMP-based dating may be less reliable when the date is uncertain or menstrual cycles are irregular. A qualified maternity-care professional may confirm or revise pregnancy dating using clinical information and ultrasound.
These independent medical references explain LMP-based pregnancy dating and trimester timing. Providing these links does not imply that ACOG or the NHS endorses Worklity.
Enter the first day your last menstrual period started.
No. It is an LMP-based estimate, and the actual delivery date may be different.
The estimate may differ when the LMP is uncertain, cycles are irregular, or ovulation timing varies.
No. This version does not calculate IVF or embryo-transfer dates.
Verify the LMP date and speak with a qualified maternity-care professional.