Pregnancy tools
Estimate your due date or work out how many weeks pregnant you are. These tools use standard pregnancy dating conventions; your care team may use different information from an ultrasound.
Pregnancy calculators
Start with the date you know best. Both tools show the assumptions behind the result.
How pregnancy dating works
Pregnancy is usually dated from the first day of the last menstrual period, not from conception. A full-term pregnancy is commonly described as 40 weeks, or 280 days, from that date. The due date calculator uses this convention and adjusts for cycle length.
An early ultrasound can revise the estimated due date, especially when the last period date is uncertain or cycles are irregular. Use the date your maternity care team gives you when one is available.
For the full dating method and the role of ultrasound, read how pregnancy due dates are calculated.
What the estimate cannot tell you
- Whether the pregnancy is developing as expected
- Your baby’s health or size
- When you will actually give birth
- Whether you need medical care
Seek urgent advice when needed
Contact your maternity care team if you notice reduced fetal movement, bleeding, fluid leaking, severe pain, or regular painful contractions. If you feel unwell or think you or your baby may be in danger, call your local emergency number.