How many weeks pregnant am I?
Pregnancy is measured in completed weeks and days from the first day of your last menstrual period — this is called gestational age. To find it, count the days from that date to today and divide by 7: the whole number is your completed weeks and the remainder is the extra days. If 100 days have passed, you are 14 weeks and 2 days pregnant (written 14+2 or 14w2d).
If you already have a due date — perhaps from a scan — choose “Due date” instead. The calculator counts back 280 days to find the equivalent starting date, so your week number matches the one your care team uses.
“14 weeks pregnant” or “week 15”?
Both are correct descriptions of the same day. At 14 weeks and 2 days you have completed 14 weeks and are now in your 15th week. Apps and books differ in which they show, so the calculator displays both.
Weeks to months of pregnancy
Months are a rough way to describe a pregnancy, because calendar months are about 4.3 weeks long. A common conversion is:
| Month of pregnancy | Weeks (approx.) | Trimester |
|---|---|---|
| Month 1 | weeks 1–4 | First |
| Month 2 | weeks 5–8 | First |
| Month 3 | weeks 9–13 | First |
| Month 4 | weeks 14–17 | Second |
| Month 5 | weeks 18–22 | Second |
| Month 6 | weeks 23–27 | Second |
| Month 7 | weeks 28–31 | Third |
| Month 8 | weeks 32–35 | Third |
| Month 9 | weeks 36–40 | Third |
Want to read about a particular week? See our pages for 8 weeks, 12 weeks, 20 weeks and 36 weeks pregnant, or browse every week from the Pregnancy Timeline.
Gestational age vs. fetal age
Gestational age includes the roughly two weeks before conception. The baby’s actual age since conception — fetal age — is about two weeks less, and the calculator shows it as “days since conception”. Medical appointments, scan reports and this site use gestational age unless they say otherwise. To see the full picture, including your due date and key dates, use the main Due Date Calculator.