Pregnancy Due Date Calculator

How This Due Date Calculator Works

This pregnancy due date calculator uses Naegele's rule — the same method most doctors use to estimate your due date. It adds 280 days (40 weeks) to the first day of your last menstrual period (LMP), assuming a standard 28-day cycle.

You can calculate your due date using three methods:

• Last Menstrual Period (LMP) — The most common method. Enter the first day of your most recent period.
• Conception Date — If you know when you conceived, this method adds 266 days from conception.
• IVF Transfer Date — For IVF pregnancies with a 5-day embryo transfer, the calculator adjusts accordingly.

How Accurate Is a Due Date?

A due date is an estimate, not a deadline. Only about 5% of babies are born on their exact due date. Most arrive within a two-week window — between 38 and 42 weeks. Your healthcare provider may adjust your due date after a first-trimester ultrasound, which is the most accurate way to confirm gestational age.

Factors that can affect accuracy include irregular cycles, uncertain LMP dates, and individual variation in ovulation timing.

Your Pregnancy Timeline

Pregnancy is divided into three trimesters, each with distinct milestones:

• First Trimester (Weeks 1–12) — Organ formation, early heartbeat detection, and the highest risk period for miscarriage.
• Second Trimester (Weeks 13–26) — Your baby grows rapidly. You'll start feeling movement (quickening) around 18–22 weeks. The anatomy scan usually happens around week 20.
• Third Trimester (Weeks 27–40) — Your baby gains weight and prepares for birth. This is when daily kick counting begins.

When to Start Counting Kicks

Most healthcare providers recommend starting daily kick counts at 28 weeks — the beginning of the third trimester. By this point, your baby has a regular sleep-wake cycle and their movements are strong enough to track. The standard method is to count 10 movements within 2 hours.

Learn how with our complete guide to kick counting, or try our free online kick counter right now. You can also print a free kick count chart to track on paper.

What to Expect at Each Week

Once you know how far along you are, check our kick counting by week guide to learn what's normal for fetal movement at your stage. Every baby has their own pattern — tracking helps you learn yours.