How many weeks pregnant am I? Calculate your current pregnancy week, trimester, and month using either your last menstrual period or your due date.
The first day of full bleeding — not spotting.
Standard is 28 days. Adjust if yours differs.
A pregnancy week calculator tells you exactly how far along you are. Enter either the first day of your last menstrual period (LMP) or your estimated due date, and you'll instantly see your current week, days into the week, trimester, month, and key pregnancy milestones. This is the same dating system doctors and midwives use to guide prenatal care.
To answer "how many weeks pregnant am I?", count the number of days from the first day of your last period to today and divide by 7. The whole number is your weeks; the remainder is the extra days. For example, 80 days since LMP means you are 11 weeks and 3 days pregnant.
Formula: Weeks pregnant = (Today − LMP) ÷ 7
The standard clinical method counts pregnancy from the first day of your last menstrual period — not from conception. That means at "2 weeks pregnant" you have not actually conceived yet; ovulation typically happens around week 2 to 3 of a 28-day cycle.
If your doctor has already given you a due date, you can work backwards. Subtract today's date from your due date to find days remaining, then subtract that from 280 days (40 weeks). Divide the result by 7 for your current pregnancy week.
Formula: Weeks pregnant = (280 − days until due date) ÷ 7
For example, if you have 100 days until your due date: 280 − 100 = 180 days pregnant, which is 25 weeks and 5 days.
Pregnancy is often described as 9 months, but it actually spans about 40 weeks — closer to 10 lunar months. Here's how the weeks map to months:
Month 1
Weeks 1–4
Month 2
Weeks 5–8
Month 3
Weeks 9–13
Month 4
Weeks 14–17
Month 5
Weeks 18–22
Month 6
Weeks 23–27
Month 7
Weeks 28–31
Month 8
Weeks 32–35
Month 9
Weeks 36–40
Pregnancy is divided into three trimesters, each with its own developmental milestones and physical changes.
First trimester
Weeks 1–13
Major organ development, morning sickness, fatigue, first ultrasound.
Second trimester
Weeks 14–27
Energy returns, baby bump shows, anatomy scan, first kicks felt.
Third trimester
Weeks 28–40+
Rapid growth, viability, prep for labor, full term at week 37.
Subtract the first day of your last period from today's date, then divide by 7. The whole number is your weeks pregnant; the remainder is the extra days.
Clinical pregnancy dating starts on the first day of your last menstrual period — not on conception. This gives you 40 weeks (280 days) to your estimated due date.
If you only know your due date, the calculator works backwards: it subtracts days remaining from 280 to find how far along you are.
Estimate due date by LMP, ovulation, conception, or IVF transfer date.
Calculate due date using last menstrual period and cycle length.
Track baby's growth week by week with trimester milestones and tips.
Log periods and predict your next cycle, ovulation, and fertile window.
Calculate your daily hydration goal during pregnancy by trimester and activity.
Measure your luteal phase length and understand what's typical.
This page is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider for prenatal care and personalized pregnancy guidance.
All the tools and guides in this cluster, in one place.
Estimate your pregnancy due date.
OpenCalculate due date from your last period.
OpenCalculate due date from conception date.
OpenCalculate due date from ovulation.
OpenFind out exactly how many weeks pregnant you are.
Current pageTrack baby's growth week by week.
OpenSee which trimester you're in.
OpenCommon pregnancy symptoms by week and what they mean.
OpenHow to read early, common, and urgent pregnancy symptoms.
Open