Pregnancy Due Date Calculator

Estimate your baby's arrival date

Calculate from LMP

First day of last menstrual period:

Average cycle length (days):

Calculate from Conception

Conception date:

Or select conception method:

IVF/Embryo Transfer

IUI

This calculator provides an estimate only. Only 5% of babies are born on their exact due date. Consult your healthcare provider.

Last Updated: 21-07-2025

What is a Pregnancy Due Date Calculator?

A Pregnancy Due Date Calculator is a helpful tool used to estimate when your baby is likely to be born. Most commonly based on the first day of your last menstrual period (LMP) or the date of conception, this calculator provides an approximate due date—typically around 40 weeks from the start of your LMP.
Knowing your estimated due date helps with prenatal planning, scheduling check-ups, and tracking your baby's development across all three trimesters.

How Does It Work?

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Two Common Methods of Calculation:

Last Menstrual Period (LMP)

The standard method used by obstetricians. It assumes ovulation occurs around day 14 of a regular 28-day cycle.

Formula: LMP Date + 280 Days (40 Weeks)

Conception Date (Ovulation Date)

If you know your exact ovulation date, this method may be more precise.

Formula: Conception Date + 266 Days

Some calculators also let you enter your IVF transfer date for assisted pregnancies.

Why Is It Important to Know Your Due Date?

Knowing your estimated due date allows both you and your healthcare provider to:

Monitor fetal growth and development
Schedule ultrasounds and diagnostic tests
Anticipate and prepare for labor and delivery
Identify preterm or post-term concerns
Make lifestyle, nutrition, and work-related decisions accordingly

Can the Due Date Change?

Yes. Your due date is an estimate, not a guarantee. Fewer than 5% of babies are born exactly on their due date. Ultrasound measurements taken in the first trimester often provide a more accurate dating, especially if your cycles are irregular.

Your doctor may revise the due date after an early ultrasound if there's a significant discrepancy from the LMP-based estimate.

What If You Don't Know Your LMP?

If you're unsure of the exact date of your last period or have irregular cycles, your provider may use:

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Early ultrasound

(6–10 weeks) for accurate fetal size

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Physical examination

(uterus size)

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Hormone level tests

(such as hCG)

In these cases, a first-trimester ultrasound is the gold standard for estimating due date.

Trimester Breakdown Based on Due Date

Once you know your due date, your pregnancy is divided into three trimesters:

First Trimester

Week 1 to Week 12

Second Trimester

Week 13 to Week 26

Third Trimester

Week 27 to Birth

Each trimester comes with specific developmental milestones, screening tests, and changes in your body.