Pregnancy Calculator – Due Date, Conception & Weeks Tracker

Pregnancy Calculator

First day of last menstrual period (LMP)

The Pregnancy Calculator (also known as a due date calculator or pregnancy due date calculator) estimates your baby’s due date, current pregnancy week, trimester, and remaining days. Whether you need a conception calculator to work backwards, a pregnancy week calculator to track weekly development, or a baby due date calculator for planning, this pregnancy tracker provides clear, step‑by‑step predictions based on your last period, conception date, or expected due date.

How Pregnancy Dates Are Calculated

1. Last Menstrual Period (LMP) method: Due date = LMP + 280 days (40 weeks).

2. Conception date method: Due date = conception date + 266 days (38 weeks).

3. Reverse method (due date known): LMP = due date – 280 days, conception = due date – 266 days.

4. Current week is calculated from LMP to today’s date.

Why Use a Pregnancy Calculator?

Plan ahead: Know your due date for medical appointments, maternity leave, and baby preparations.
Track development: Each week brings new fetal milestones – our pregnancy week calculator shows you where you are.
Understand trimesters: First (0‑12w), second (13‑27w), third (28‑40w) – each with different symptoms and developments.
Share with your provider: Provide accurate dates to your obstetrician.

This pregnancy due date calculator is based on standard medical formulas. For individualised care, always consult your healthcare provider. Bookmark this pregnancy tracker to use it throughout your pregnancy.

Understanding Pregnancy Trimesters

Pregnancy is divided into three trimesters. The first trimester (weeks 0‑12) is when the baby’s organs form. The second trimester (13‑27 weeks) is a period of rapid growth. The third trimester (28‑40 weeks) is when the baby gains weight and prepares for birth. Our pregnancy week calculator tells you exactly which week and trimester you are in.

Frequently Asked Questions About Pregnancy Dates

Can I use this if my cycle is irregular? Yes, but the estimate may be less accurate. Ultrasound dating is more precise.
How many weeks is a full‑term pregnancy? 40 weeks (about 9 months) from LMP, or 38 weeks from conception.
What if I already know my due date? Use the “Due date (reverse)” mode to calculate your LMP and conception date.
Is this a medical device? No, it is for informational purposes. Always confirm with your doctor.

How to Use This Pregnancy Tracker Throughout Your Journey

Save the result page or bookmark the link. As time passes, you can re‑calculate using the same LMP or due date to update your current week. This makes it a dynamic pregnancy tracker without needing to create an account.

Bookmark this pregnancy calculator to use it as your go‑to due date calculator, pregnancy due date calculator, conception calculator, and baby due date calculator. Share it with family and friends who are expecting.

Step‑by‑Step Manual Example

LMP: January 1, 2025 | Today: March 15, 2025

Due date = Jan 1 + 280 days = October 8, 2025

Days since LMP = 73 → weeks = 10 weeks + 3 days

Trimester = First (0‑12 weeks)

Weeks remaining = 40 – 10 = 30 weeks

Frequently Asked Questions about Pregnancy & Due Date

How is the due date calculated?

The most common method is Naegele’s rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). If you know conception date, add 266 days (38 weeks).

How accurate is this pregnancy due date calculator?

It provides a good estimate, but only about 5% of babies are born exactly on their due date. Use it as a guide and consult your healthcare provider.

What is the difference between LMP and conception date?

LMP is the first day of your last period. Conception usually happens about 14 days after LMP. The calculator can use either to estimate the due date.

Can I use this as a pregnancy tracker?

Yes, after entering your dates you will see your current week, trimester, weeks remaining, and progress – perfect for tracking your pregnancy journey.