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Pregnancy Calculator

Estimate your pregnancy timeline and key milestones from your last period.

Your details

Results

Estimated due date
Apr 13, 2027
223 days remaining
Gestational age
8w 0d
Day 56 of 280
Current trimester
1st trimester
Weeks 1–13
Conception estimate
Jul 21, 2026
≈ LMP + 14 days
Pregnancy progress
20% · week 8 of 40
Week 0Week 13Week 27Week 40
Key milestones
MilestoneWeekDateStatus
First heartbeat
Embryonic heartbeat often detectable
6w0dAug 18, 2026Reached
End of 1st trimester
Risk of miscarriage drops sharply
13w0dOct 6, 2026Upcoming
Anatomy scan
Detailed ultrasound usually performed
20w0dNov 24, 2026Upcoming
Viability
Survival possible with intensive care
24w0dDec 22, 2026Upcoming
End of 2nd trimester
Third & final trimester begins
27w0dJan 12, 2027Upcoming
Early term
Considered early-term delivery
37w0dMar 23, 2027Upcoming
Full term
Ideal delivery window opens
39w0dApr 6, 2027Upcoming
Estimated due date
40 weeks from LMP
40w0dApr 13, 2027Upcoming
Estimated due date is calculated using Naegele's rule (LMP + 280 days), adjusted for cycle length. Only about 5% of babies are born on their due date — most arrive within two weeks of it. Always consult your healthcare provider for clinical dating.

What is the Pregnancy Calculator?

A pregnancy calculator estimates how far along you are by counting weeks from the first day of your last menstrual period (LMP). It shows your current gestational age, trimester, and key milestones such as the end of the first trimester, viability, and full term.

Pregnancy Calculator formula

Gestational age = (today's date − LMP date) in days ÷ 7, expressed as weeks + days. A full-term pregnancy lasts 40 weeks (280 days). Trimesters: 1st = weeks 1–13, 2nd = weeks 14–27, 3rd = weeks 28–40. Full term is 39–40 weeks; 37–38 weeks is early term.

How to use the Pregnancy calculator

  1. 1Enter the first day of your last menstrual period.
  2. 2Optionally enter your average cycle length for a more accurate estimate.
  3. 3Click Calculate to see your current gestational age in weeks and days.
  4. 4Review your trimester and upcoming milestone dates.

Example calculation

If your LMP was January 1 and today is March 15 (73 days later), you are 73 ÷ 7 = 10 weeks and 3 days pregnant, placing you in week 11 of the first trimester.

Frequently asked questions

How is pregnancy calculated in weeks?
Pregnancy is counted from the first day of your last menstrual period, not from conception. So at conception you are technically about 2 weeks pregnant, and a full-term pregnancy lasts about 40 weeks (280 days) from LMP.
Which trimester is the hardest?
Many find the first trimester (weeks 1–13) the toughest due to nausea, fatigue, and hormone changes. The second trimester (weeks 14–27) is often called the honeymoon phase, and the third (weeks 28–40) brings physical discomfort as the baby grows.
How many weeks is full term?
Full term is 39 weeks 0 days through 40 weeks 6 days. Births at 37–38 weeks are 'early term,' 41 weeks is 'late term,' and 42+ weeks is 'post term.'
Is the pregnancy calculator accurate?
Counting from LMP is accurate for women with regular 28-day cycles but can be off by a week or more if cycles are irregular. An early ultrasound (before 12 weeks) gives the most precise dating — discuss results with your OB-GYN.

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