Estimate your due date, current gestational age, and trimester from the first day of your last menstrual period, adjusted for your cycle length.
How it works
- Select the first day of your last menstrual period.
- Adjust your average cycle length if different from the 28-day norm.
- View your estimated due date and current trimester phase.
Frequently asked questions
How accurate is the due date?
Only about 1 in 20 babies arrive on the exact due date. It marks the center of a normal delivery window (37 to 42 weeks).
What if my cycle is not 28 days?
The tool adjusts: a longer cycle pushes the due date later, since ovulation happens later.
Should I rely on this instead of my doctor?
No. This is an educational estimate; your provider's dating ultrasound is the medical standard.
What if my LMP was irregular?
LMP-based calculations assume a standard 28-day cycle. If yours differs, use an ultrasound dating instead — your healthcare provider can give you the most accurate date.