Pregnancy Week Calculator
See exactly how many weeks and days pregnant you are, plus which trimester you are in.
How the Pregnancy Week Calculator Works
Enter the first day of your last menstrual period (LMP) and the calculator works out how many weeks pregnant you are, which trimester you are in, and your estimated due date. Pregnancy is divided into three trimesters: weeks 1 to 13, weeks 14 to 27, and weeks 28 to 40.
The result is an estimate based on the standard 40-week count from LMP. Real pregnancies vary, and scan-based dating can differ by days or even weeks. This tool is for general information only and is not a substitute for medical advice from your clinician or midwife.
Frequently Asked Questions
How is my due date calculated?
Why is pregnancy counted as 40 weeks?
What if I do not know my last period date?
Is the due date exact?
More Women's Health Tools
Period Calculator
Forecast your upcoming periods using the date of your last period and your average…
Use nowOvulation Calculator
Predict your ovulation date and fertile window from your last period and c…
Use nowFertility Window Calculator
Pinpoint your fertile window and best conception days based on your cycle.…
Use nowPregnancy Weight Gain Calculator
Check your recommended healthy weight-gain range based on your pre-pregnancy BMI a…
Use now