📌 Based on a standard 40-week (280 day) pregnancy from LMP. Always confirm with your healthcare provider.

About the Pregnancy Calculator

Pregnancy is a 40-week journey filled with milestones, appointments, and preparations. Our Pregnancy Calculator helps you track every step from conception to birth. Enter your last menstrual period (LMP) date, and get your estimated due date, current week of pregnancy, current trimester, and a timeline of key prenatal milestones to look forward to.

Whether you've just discovered you're pregnant or are deep into your third trimester, this tool keeps you oriented to where you are in the journey and what's coming next.

How It Works

Enter the first day of your last menstrual period (or your conception date, if known). The calculator uses Naegele's Rule (LMP + 280 days) to compute the estimated due date, and derives your current gestational age and trimester from today's date.

Formula / Key Reference

Estimated Due Date = LMP + 280 days

Gestational Age = Current Date − LMP

Trimester:

1st: Weeks 1–13

2nd: Weeks 14–26

3rd: Weeks 27–40+

Real-World Example

LMP: October 1, 2025

Estimated due date: October 1 + 280 days = July 8, 2026

As of April 4, 2026:

Gestational age: 26 weeks, 3 days

Trimester: Second trimester (final weeks)

Next milestone: 27 weeks — entering third trimester in 4 days

Key upcoming milestones:

27 weeks (Apr 8): Third trimester begins

28 weeks (Apr 15): Growth ultrasound typically scheduled

32 weeks (May 13): Prenatal visits become every 2 weeks

36 weeks (Jun 10): Weekly appointments begin

37 weeks (Jun 17): Early term (37–38 weeks)

39 weeks (Jul 1): Full term

40 weeks (Jul 8): Due date

Common Uses

  • Tracking weekly progress through all three trimesters
  • Planning prenatal appointments around standard gestational milestones
  • Preparing for screening tests at specific weeks (first-trimester screen, anatomy scan)
  • Planning maternity/paternity leave based on the estimated due date
  • Sharing pregnancy progress milestones with family and friends

Frequently Asked Questions

What are the three trimesters? ▼
The first trimester covers weeks 1–13, when all major organs form. The second trimester (weeks 14–26) is often the most comfortable, as morning sickness often subsides and energy returns. The third trimester (weeks 27–40+) involves rapid fetal growth, preparation for birth, and increasing prenatal checkups.
When is a baby considered full term? ▼
The American College of Obstetricians and Gynecologists (ACOG) defines full term as 39–40 completed weeks. Early term is 37–38 weeks; late term is 41 weeks; post-term is 42+ weeks. Babies born before 37 weeks are considered preterm and may require additional medical support.
When should I schedule my first prenatal appointment? ▼
Most OBs and midwives recommend the first prenatal visit between 8 and 10 weeks of pregnancy. An earlier appointment (around 6–8 weeks) may be scheduled if you have risk factors or used fertility treatments. If you think you're pregnant, contact your healthcare provider promptly to schedule.