Due Date Calculator
Estimate your baby's due date from your last period, conception date or IVF transfer — with gestational age, trimester and key milestones. Runs in your browser.
How your due date is estimated
A full-term pregnancy is counted as 40 weeks — 280 days — from the first day of your last menstrual period (LMP), not from conception. This is Naegele's rule, and it assumes a regular 28-day cycle in which you ovulate around day 14. Because dating starts two weeks before you actually conceive, you are considered "four weeks pregnant" about the time of a missed period. If your cycles are longer or shorter than 28 days, ovulation shifts and the calculator moves the due date to match. Calculating from a known conception date counts 266 days instead, and an IVF due date is worked out from the transfer date and the embryo's age, which makes it the most precise.
Pregnancy milestones
The milestone table above marks the common landmarks: the end of the first trimester at 13 weeks, the mid-pregnancy anatomy scan around 20 weeks, the point of viability near 24 weeks, the start of the third trimester at 28 weeks, and "full term" from 37 weeks. The estimated due date sits at 40 weeks, but a normal birth can happen any time from 37 to 42 weeks, and only a small minority of babies arrive exactly on the estimated day.
Frequently Asked Questions
How is my due date calculated?
Which method should I use?
What if my cycle isn't 28 days?
Is this a substitute for medical advice?
Related tools
See how far along you are week by week, or count down to the big day with the Calendar & Date tools.