Pregnancy & Due Date Calculator
Calculate how many weeks pregnant you are and your estimated due date based on your last menstrual period.
This tool is for informational purposes only. The estimated due date may differ from ultrasound findings and your doctor's assessment. Do not miss regular check-ups during pregnancy.
How Is Pregnancy Week Calculated?
The pregnancy calculator is designed to guide expectant mothers through their most exciting wait. Medically, pregnancy begins from the first day of the last menstrual period (LMP). An average pregnancy lasts 40 weeks (280 days). This tool uses the Naegele method to determine your estimated due date by adding 7 days to your last period date and going back 3 months.
What Are the Trimester Periods?
The pregnancy process is divided into three main periods (trimesters). Each period brings different physical and hormonal changes.
| Period | Weeks | Key Developments |
|---|---|---|
| 1st Trimester | Weeks 1–12 | Organ development, heartbeat begins, nausea and vomiting |
| 2nd Trimester | Weeks 13–26 | Movements felt, sex can be determined, nausea subsides |
| 3rd Trimester | Weeks 27–40 | Rapid growth, preparation for birth, position monitoring |
The Importance of Week-by-Week Pregnancy Tracking
Every week brings different developments in your baby and your body. Knowing your pregnancy week is critical for timing screening tests, tracking the baby's developmental stages, and planning the birth preparation process. However, keep in mind that only 5% of babies are born on the exact calculated date — this date is only an estimate.
- In the first trimester, do not miss the NT ultrasound and maternal blood screening (combined test, weeks 11–13+6).
- The OGTT test at weeks 24–28 screens for gestational diabetes (GDM); early detection is important.
- The week 20 anomaly ultrasound is the most comprehensive scan for assessing all of the baby's organ structures — plan the appointment early.
- Folic acid supplementation should begin before conception and continue for at least the first 12 weeks.