Pregnancy & Due Date Calculator
Use this pregnancy calculator to estimate your due date, see how many weeks pregnant you are and find out your probability of giving birth on certain dates.
Whilst every effort has been made in building this pregnancy calculator, we are not to be held liable for any special, incidental, indirect or consequential damages or monetary losses of any kind arising out of or in connection with the use of the converter tools and information derived from the web site. This pregnancy calculator is here purely as a service to you, please use it at your own risk. Do not use calculations for anything where loss of life, money, property, etc could result from inaccurate conversions.
Please see the full disclaimer for more information.
How far along am I?
To calculate how many weeks pregnant you are, this calculator looks at the first day of your last menstrual period (LMP) and compares it to today's date. The first day of your LMP counts as the first day of your pregnancy. This calculation is based upon an average cycle of 28 days. If your cycle is different to 28 days, your calculation will vary based upon this.
You will find that the sonographer at your first ultrasound scan (often called the dating scan) will give you a more accurate idea of how many weeks pregnant you are by measuring your baby from its head to its bottom to form a determination.
How is my due date calculated?
This pregnancy calculator uses one of two methods to work out your due date. If you fill in the start date of your last period, it takes that date and adds 40 weeks (280 days) to that date (assuming you've chosen a 28 day average cycle). If you've chosen a different cycle, it will add or subtract days based upon that. If you choose to calculate by ultrasound date, the calculator will work out your due date based upon how far along you are on that date. This will likely yield a more accurate result.
How accurate is this pregnancy calculator?
It is important to remember that this pregnancy calculator is meant to be a bit of fun and the results contain guesswork (as with all 'predictions' about the future). Assuming it will be born naturally, there's obviously no way of knowing for certain when your baby will arrive. It is worth noting that only 5-7% of babies arrive on their due date. The vast majority are born two weeks either side. This calculator, as with all due date calculators, should be used only as a guide, to give you a little help with planning for your baby's arrival.
How do your due date graphs work?
The graphs display possible due dates based upon baby arrival data from a survey carried out by Spacefem.com. This survey relied upon correct information being input by each of the 9,000+ Mums who took part; it was not a scientific study.
If you have any problems using this pregnancy calculator, please contact me.