Pregnancy due date calculator
Enter the first day of your last period to see your due date and how far along you are.
Pregnancy due date calculator
How to use it
- Enter the date your last period started.
- Change the cycle length if yours is not 28 days.
- Read your due date, weeks of pregnancy and trimester.
- Confirm the date with an early ultrasound.
Your entries stay in your browser. Nothing is sent to us. The result is for information and is not a diagnosis.
How the due date is calculated
Pregnancy is counted from the first day of the last period and lasts about 280 days, or 40 weeks. This is Naegele's rule. For a cycle longer or shorter than 28 days, the difference is added or taken away.
Trimesters
| Trimester | Weeks |
|---|---|
| First | 1 to 12 |
| Second | 13 to 26 |
| Third | 27 to 40 |
Care during pregnancy
Register with a lady doctor or the nearest health centre early. Take folic acid and iron as advised, attend your check-ups and plan the delivery at a hospital. Bleeding, severe pain, severe headache, swelling of the face or a baby that stops moving are emergencies.
See women's health at the clinic and the ovulation calculator.
Questions
How accurate is a due date calculator?
It is a good estimate if your cycles are regular. An ultrasound in the first three months is more accurate.
How many weeks is a full-term pregnancy?
37 to 42 weeks. The due date marks 40 weeks.
What if I do not remember my last period?
A doctor can date the pregnancy by ultrasound.
Prepared by the team at Babar Homeopathic Clinic & EyeBar Optical, Kangan Pur. Last updated 3 October 2026. See our medical disclaimer.
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