33 weeks pregnant
Enter the first day of your last period to get a due date and the current week. The example here follows a person who is at week 33.
How it works
The due date is 280 days after the first day of your last period. Weeks of pregnancy are the days since that first day divided by 7. Week 33 is 231 days.
Worked example
Say the first day of the last period is 16 September. The due date is 280 days later, on 23 June. After 231 days the date is 5 May. 231 divided by 7 is 33. That is the start of week 33. The 49 days left run to the due date. This example uses a 365-day year.
Common questions
What if my cycle is not 28 days?
The 280 day rule assumes ovulation near day 14. If your cycle is much longer or shorter, your doctor may adjust the due date, often with an ultrasound. With a 35-day cycle some clinicians add 7 days, which would move 23 June to 30 June.
Does a leap year change the due date?
It can. A year with an extra day in February moves dates after that day by one. The calculator above uses the real calendar for your dates. If the span from 16 September includes a 29 February, 23 June reads one day earlier, as 22 June.
How many months is 33 weeks pregnant?
About 7.6 months. A pregnancy is 40 weeks, a little over 9 calendar months. Months are only a rough guide. At 33 weeks there are 49 days to the due date.
Which trimester is week 33?
Third trimester. The first trimester covers weeks 1 to 13, the second covers weeks 14 to 27 and the third runs from week 28 to the birth. Week 33 is week 6 of the third trimester.
Why do weeks start from the last period and not conception?
Most people know the date of their last period but not the day of conception. Counting from the last period gives everyone the same starting point. A pregnancy is about two weeks longer on paper than from conception. Counted from conception, this would be week 31, which is 217 days.