Pregnancy Due Date Calculator

Calculate Your Baby's Due Date Instantly

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Due Date Calculator
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Due Date
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How to Use This Due Date Calculator

Our free due date calculator gives you accurate estimates in seconds. Enter your numbers above and hit Calculate — results update instantly.

All calculations use current 2026 rates and formulas. Results are estimates to help you plan — always verify with a licensed professional for final numbers.

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Frequently Asked Questions

How is my due date calculated?
Your due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period. This is called Naegele rule and is the standard method used by doctors worldwide.
How accurate is a due date calculator?
Due date calculators give an estimated due date. Only about 5% of babies are born on their exact due date. Most babies arrive within 2 weeks before or after the estimated date.
Can I calculate due date by conception date?
Yes. If you know your conception date, add 266 days (38 weeks) to get your estimated due date. This method can be more accurate if you tracked ovulation.
What is a full-term pregnancy?
A full-term pregnancy is 39-40 weeks. Early term is 37-38 weeks, late term is 41 weeks, and post-term is 42 weeks or beyond.
How do I count pregnancy weeks?
Pregnancy weeks are counted from the first day of your last menstrual period. At conception, you are considered 2 weeks pregnant. A full-term pregnancy is 40 weeks.

Pregnancy Due Date Calculator

Use this due date calculator to estimate a pregnancy due date based on common dating methods. The result is an estimate, not a medical diagnosis. Your doctor or midwife may adjust the due date based on ultrasound measurements and clinical information.

Due Date by Last Menstrual Period

The most common method estimates the due date from the first day of the last menstrual period. A standard pregnancy is often estimated at about 40 weeks from that date, although actual delivery dates can vary.

Due Date by Conception Date

If you know the estimated conception date, the calculator can estimate the due date from that point. This can be useful when cycle dates are uncertain or when the conception window is better known.

IVF Due Date

For IVF pregnancies, due date estimates may be based on embryo transfer date and embryo age. IVF dating can be more precise than cycle-based estimates, but your healthcare provider should confirm it.

Ultrasound Due Date

Ultrasound dating may be used to adjust the due date, especially early in pregnancy. If ultrasound dating differs from period-based dating, medical guidance is usually more reliable than a simple calculator.

Pregnancy Weeks

Pregnancy weeks are commonly counted from the first day of the last menstrual period. This means pregnancy dating usually starts before conception actually occurs.

FAQ

How is a due date calculated?

A due date is commonly estimated as about 40 weeks from the first day of the last menstrual period.

Is the due date exact?

No. A due date is an estimate. Many babies are born before or after the estimated due date.

Can I calculate a due date from conception date?

Yes. If you know the estimated conception date, it can be used to estimate a pregnancy due date.

How does IVF due date calculation work?

IVF due date estimates usually use embryo transfer date and embryo age.

Can ultrasound change my due date?

Yes. A healthcare provider may adjust the due date based on ultrasound measurements, especially in early pregnancy.

Last checked: June 23, 2026