25 weeks pregnant
Week 25 of pregnancy means 175 days since the last period began. Use the form to place your own dates, or read the example below.
How it works
Add 280 days to the first day of your last period to get the due date. To find the current week, count the days since that day and divide by 7. At 175 days along, 105 days remain.
Worked example
Say the first day of the last period is 20 January. The due date is 280 days later, on 27 October. After 175 days the date is 14 July. 175 divided by 7 is 25. That is the start of week 25. The 105 days left run to the due date. This example uses a 365-day year.
Common questions
Which trimester is week 25?
Second 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 25 is week 12 of the second 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 23, which is 161 days.
How accurate is a due date?
Only a small share of babies arrive on the due date. Most arrive within a couple of weeks either side. Treat the date as the middle of a window. Here the due date is 27 October, and 105 days remain from week 25.
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 27 October to 3 November.
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 20 January includes a 29 February, 27 October reads one day earlier, as 26 October.