Find your pregnancy week, trimester, and due date on any date
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You are
10w 0d
Trimester 1
Estimated due date
October 8, 2026
Days to go
210 days
First day of last period (LMP)Estimated due date
About 25% through the 40 weeks
How it is calculated
Gestational age = as-of date − LMP · Due date = LMP + 280 days
Gestational age is the completed days since the last period, shown as weeks and days. The due date is the LMP plus 280 days (Naegele's rule). Trimesters: 1 (≤12w), 2 (13–26w), 3 (27w+).
What is a pregnancy week calculator?
A pregnancy week calculator tells you how far along a pregnancy is on a chosen date, expressed as completed weeks and days of gestational age. You can start from the first day of the last menstrual period (LMP), the estimated due date, or the date of conception, and the calculator converts whichever you provide into a consistent gestational age. It also shows the current trimester, the estimated due date (LMP + 280 days), how far through the 40-week term you are, and how many days remain — making it easy to track milestones and appointments.
How to use it
1. Choose what you want to start from: last menstrual period, due date, or conception date.
2. Enter that date.
3. Set the 'as of' date — the day you want the pregnancy age calculated for. Tap 'Today' to use the current date.
The calculator shows the gestational age in weeks and days, the trimester, the due date, the days remaining, and a progress bar across the term. Because the page is built statically, the reference date is an input you control rather than fixed to the moment you load it.
How it is calculated
Everything is reduced to the LMP, which is gestational day 0:
From a due date: LMP = due date − 280 days
From conception: LMP = conception − 14 days
Gestational age = completed days from LMP to the chosen date, shown as weeks and days
Due date = LMP + 280 days (Naegele's rule)
Trimesters: first up to week 12, second weeks 13–26, third from week 27. For an LMP of January 1, 2026 and an 'as of' date of March 12, 2026, the gestational age is exactly 10 weeks 0 days.
Reading your results
Gestational age is given in completed weeks and days — for example '10w 3d' means ten full weeks plus three days. The first trimester runs to the end of week 12, the second covers weeks 13–26, and the third runs from week 27 to birth. The progress bar and days-remaining figure are based on the 280-day term, but a normal full-term birth can occur anywhere from 37 to 42 weeks. Treat the due date as an estimate; an early ultrasound provides the most accurate dating.
Frequently asked questions
How are pregnancy weeks counted? ▾
From the first day of the last menstrual period, not from conception. So at ovulation — about two weeks after the LMP — you are already counted as 'two weeks pregnant'. Weeks are completed weeks plus extra days, e.g. 10w 3d.
How do trimesters work? ▾
The first trimester runs through week 12, the second from weeks 13 to 26, and the third from week 27 until birth. Each brings different developmental milestones and recommended check-ups.
Why is my due date 40 weeks but pregnancy is '38 weeks'? ▾
Gestational age is counted from the last period (40 weeks to the due date), while fetal age is counted from conception, about two weeks later (38 weeks). Both describe the same pregnancy from different starting points.
What if I only know my due date or conception date? ▾
That's fine — choose the matching mode. The calculator converts a due date or conception date back to an equivalent last-period date and computes the gestational age from there.
This pregnancy week calculator is for general informational and educational purposes only and is not medical advice. Gestational age and due dates are estimates that your healthcare provider may revise after an ultrasound. Always follow professional medical guidance during pregnancy.