Pregnancy Due Date Calculator
Free calculator for Australia - LMP, IVF & Conception methods
How to Calculate Your Due Date
Your due date is an estimate of when your baby will arrive. While only about 5% of babies arrive exactly on their due date, knowing when to expect your baby helps you prepare for their arrival and ensures proper prenatal care throughout your pregnancy.
Calculation Methods
1
Last Menstrual Period (LMP)
The most common method. Your due date is calculated as 280 days (40 weeks) from the first day of your last period, adjusted for your cycle length.
2
Conception Date
If you know when you conceived or ovulated, this can be more accurate. Your due date is 266 days (38 weeks) from conception.
3
IVF Transfer Date
For IVF pregnancies, the due date is based on your embryo transfer date and embryo age. Often the most accurate method.
4
Ultrasound Scan
Early ultrasounds (8-13 weeks) provide accurate dating based on your baby's size. Your provider may adjust your due date accordingly.
Your Pregnancy Timeline
First Trimester
Weeks 1-13
Major organs and structures develop
Second Trimester
Weeks 14-27
Baby grows rapidly, you may feel movement
Third Trimester
Weeks 28-40+
Baby gains weight and prepares for birth
Frequently Asked Questions
How accurate is a due date calculator?
Due date calculators provide an estimate, not an exact date. Only about 5% of babies arrive on their exact due date. Most babies are born between 37 and 42 weeks of pregnancy. Your healthcare provider may adjust your due date based on ultrasound scans and other factors.
Can my due date change?
Yes, your due date can be adjusted based on early ultrasound scans, especially if performed between 8-13 weeks. These scans can provide a more accurate estimate of your baby's gestational age.
What if I don't know my last menstrual period?
If you don't remember your last menstrual period, you can use the conception date calculator if you know when you conceived. Alternatively, an early pregnancy ultrasound can help determine your due date.
How is a due date calculated for IVF pregnancies?
IVF due dates are calculated based on your embryo transfer date and the age of the embryo at transfer. For a 3-day embryo transfer, 263 days are added. For a 5-day (blastocyst) transfer, 261 days are added. This method is very accurate since the exact fertilization date is known.
When Should You See a Doctor?
Once you've calculated your due date, it's important to schedule your first prenatal appointment. Most healthcare providers recommend scheduling your first visit between 6-8 weeks of pregnancy.
Need Fertility Support?
Whether you're planning to conceive or already pregnant, our AHPRA-registered doctors can provide expert fertility consultations and IVF referrals online.
Book Fertility ConsultationDisclaimer: This calculator provides an estimate only. Your actual due date may vary. Always consult with your healthcare provider for accurate pregnancy dating and prenatal care. HeyDoc's due date calculator is for informational purposes and should not replace medical advice from your doctor or midwife.