Pregnancy (Due Date) Calculator

703 Users are discussing this topic

PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

This pregnancy due date calculator will give you a rough idea of when your baby should be born. If you know the date of the first day of your last menstrual period (LMP), or have already had your first ultrasound scan, you can use this tool. Please remember that the result will not necessarily be the day that your baby arrives. The actual date may be any time from 38 to 42 weeks in most pregnancies. If problems occur you may be advised that delivering your baby earlier is the safest option.

For advice on recognising signs that you are going into labour, or for information on some types of pain relief in labour, follow the links. We also have information on how your baby is monitored in labour.

Calculate from 1st day of last menstrual period (LMP)
Enter LMP (dd/mm/yy - eg, 20 01 2009)
Cycle length days
Estimated date of delivery (EDD) 
Gestation (number of weeks pregnant)   weeks days

Calculations from obstetric ultrasound scan
Enter scan date (dd/mm/yy - eg, 20 01 2009)
Scan gestation weeks days
EDD by scan
Gestation today weeks days

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Huw Thomas
Current Version:
Peer Reviewer:
Hilary Cole
Document ID:
2531 (v26)
Last Checked:
Next Review:
Patient Access app - find out more Patient facebook page - Like our page