Health & Fitness · Free tool
Pregnancy Calculator
Calculate due date, current week, and trimester from last menstrual period. Free, private, no data leaves your browser.
Estimated due date
January 27, 2027
Current progress
0w 0d
Trimester
1st trimester
Conception (est.)
May 6, 2026
How it works
- Due date = LMP + 280 days (Naegele's rule).
- Conception is estimated at LMP + 14 days (assumes a 28-day cycle).
- Trimesters: 1st = weeks 1–12, 2nd = 13–26, 3rd = 27–40.
Estimates only — your provider's dating ultrasound is more accurate.
What it does
Estimate your due date, current week of pregnancy, and trimester from either the first day of your last menstrual period (LMP) or a known conception date. Uses the standard Naegele's rule of LMP + 280 days, the same formula most practitioners and apps use for a first-look estimate.
This is a planning tool, not a medical device — real due dates shift based on ultrasound dating, ovulation timing, and individual cycle variation. For fertility-window planning before conception, use the ovulation calculator; for ongoing appointments and milestones, keep it beside your prenatal-care schedule.
How to use it
- Pick LMP or conception-date mode.
- Enter the relevant date.
- Read your estimated due date and current pregnancy week.
- See which trimester you're in and the estimated conception date.