Pregnancy Due Date & Conception Date Calculator

What Is a Pregnancy Due Date Calculator?

A pregnancy due date calculator estimates the day your baby is expected to arrive, usually called the estimated due date (EDD). It also shows how many weeks pregnant you are today, your likely conception date and the key dates along the way. Enter one date, such as the first day of your last period, and the calculator builds your full pregnancy timeline in seconds.

It is a free and simple planning tool for anyone who is expecting, trying to conceive or curious about how pregnancy dates work. Use it to plan doctor visits, maternity leave, travel and baby preparations with more confidence.

How to Use This Due Date and Conception Date Calculator

1. Choose your method. Pick last menstrual period (LMP), conception date, due date, IVF transfer date or ultrasound.
2. Enter your date. Add the date that matches the method you chose. For the LMP method, you may also need your average cycle length.
3. Get your results. See your estimated due date, conception date, current pregnancy week and trimester at a glance.

You can switch between methods at any time to compare results. If your dates differ by a few days, that is normal, because every method is an estimate.

How Is Your Due Date Calculated?

Doctors and midwives count pregnancy as 40 weeks, or about 280 days, starting from the first day of your last menstrual period. Conception usually happens about two weeks later, around ovulation. That is why you are already counted as "two weeks pregnant" on the day you conceive.

Last Menstrual Period (LMP)

The most common method uses Naegele's rule: add 280 days to the first day of your last period. If your cycle is longer or shorter than 28 days, the date is adjusted to match your own ovulation timing.

Conception Date

If you know when you conceived, your due date is about 266 days (38 weeks) after conception.

IVF Transfer Date

For IVF, the due date depends on the embryo age at transfer. A day 5 embryo transfer adds about 261 days, and a day 3 embryo transfer adds about 263 days.

Ultrasound Dating

An early ultrasound measures the baby and estimates gestational age. It is especially helpful when your last period date is uncertain or your cycles are irregular.

Pregnancy Trimesters at a Glance

Trimester	Weeks	What to expect
First trimester	Week 1 to 12	Early development, first scans and common symptoms such as nausea and tiredness.
Second trimester	Week 13 to 27	Energy often returns, the anatomy scan is done and baby movements are usually felt.
Third trimester	Week 28 to 40	Rapid growth, regular check-ups and final preparation for labour and birth.

How Accurate Is a Due Date?

A due date is a helpful guide, not a promise. Only a small share of babies are born exactly on their due date. Most arrive within a couple of weeks either side, and a pregnancy is considered full term from 39 to 40 weeks. Your doctor may update your due date after an early ultrasound, so always follow your healthcare provider's advice.

Who Can Use This Calculator?

• Women who have just found out they are pregnant
• Couples trying to conceive who want to understand ovulation and conception timing
• Women having IVF treatment who want a due date from the transfer date
• Partners, family members and friends planning around a due date

Frequently Asked Questions

How do I calculate my due date from my last period?

Add 280 days (40 weeks) to the first day of your last menstrual period. This calculator does it for you and adjusts for your cycle length.

Can I find my conception date from my due date?

Yes. Choose the due date method and enter your date. The calculator counts back about 266 days to estimate when conception most likely happened.

How many weeks pregnant am I?

Your pregnancy week is counted from the first day of your last period, or from the equivalent date given by your chosen method. The calculator shows your current week and day automatically.

Is this calculator accurate for irregular cycles?

The result is an estimate. If your cycles are irregular, an early ultrasound gives a more reliable due date, so try the ultrasound method or ask your doctor.

Can I use this calculator for IVF pregnancy?

Yes. Select the IVF transfer method, enter your transfer date and choose whether it was a day 3 or day 5 embryo transfer.

When will I have my first ultrasound?

Many providers offer a dating scan between 8 and 14 weeks. Your doctor or midwife will tell you the best timing for you.

Note: This calculator is for information only and does not replace medical advice. Please talk to your doctor or midwife about your pregnancy and your exact due date.