What This Tool Does
The pregnancy due date calculator estimates due date, current gestational age, delivery window (plus or minus 7 days), and key milestone dates from the first day of the last menstrual period and cycle length.
Calculation Method
- Standard pregnancy length is estimated as 280 days (40 weeks).
- If cycle length is not 28 days, a day adjustment is applied as
cycle length - 28. - Due date = first day of LMP + adjusted pregnancy length.
- Estimated conception date is based on around day 14 with cycle adjustment.
How to Use
- Select the first day of your last menstrual period.
- Enter cycle length as an integer from 20 to 45 (default 28).
- Click
Calculate Due Date. - Review gestational week, progress, milestones, and stage guidance.
Result Fields
- Estimated Due Date: reference date for expected delivery.
- Estimated Conception Date: cycle-adjusted estimation.
- Delivery Window: date range from 7 days before to 7 days after due date.
- Time to Due Date: remaining or overdue days relative to today.
- Key Milestones: dates for week 12, 27, 37, and 40.
Typical Use Cases
- Pregnancy timeline and routine planning
- Prenatal visit scheduling
- Family preparation and task coordination
- Gestational progress tracking
Notes
- This tool is for date estimation and does not replace medical diagnosis.
- Irregular cycles, delayed ovulation, or special conditions may affect accuracy.
- Seek medical care promptly for abdominal pain, bleeding, water breaking, or other warning signs.