How many weeks pregnant am I? How pregnancy weeks are counted
The short answer
Count the weeks from the first day of your last period, not from the day you conceived. If your last period started 8 weeks and 3 days ago, you are 8 weeks and 3 days pregnant. A pregnancy is counted as 40 weeks (280 days) from that date to the due date. The free due date calculator does the counting for you.
Why count from the last period?
Most people know the date their last period started, but very few know the exact day they conceived. So doctors and health workers count from the period. This means that in the first two weeks of “pregnancy” you are not actually pregnant yet: the egg is usually released around two weeks after the period starts.
So when you are “6 weeks pregnant”, conception happened about 4 weeks earlier.
How to count your weeks
- Find the first day of your last period.
- Count the days from then to today.
- Divide by 7. The whole number is your weeks; what is left over is your days.
For example, from 1 January to 1 March 2026 is 59 days: 8 weeks and 3 days. Written by health workers as “8+3”.
If your cycles are usually longer than 28 days, you probably ovulated later, so you may be a little less far along. With a 35-day cycle, it is about a week less. The calculator adjusts for this when you enter your cycle length.
Weeks, months and trimesters
40 weeks is a little over 9 calendar months, which is why “9 months” and “40 weeks” are both used. Health workers use weeks because months are different lengths.
| Stage | Weeks |
|---|---|
| First trimester | Up to 13 weeks and 6 days |
| Second trimester | 14 weeks to 27 weeks and 6 days |
| Third trimester | From 28 weeks |
| Term | 37 weeks to 41 weeks and 6 days |
When the date can change
Dating by the last period is less reliable if:
- your cycles are irregular or you are unsure of the date
- you got pregnant soon after stopping hormonal birth control, or after a pregnancy or while breastfeeding
- you had bleeding in early pregnancy that you thought was a period
An ultrasound scan early in pregnancy usually gives a more accurate date. If your scan date is different from your period date, your health worker will tell you which to use. Their date always comes first.
Using Nepali (BS) dates
If you remember your last period in Bikram Sambat, don’t count BS months: they have 29 to 32 days and change every year. Use the Nepali (BS) due date calculator, which converts the date and shows your weeks, due date and Nepal’s check-up timing in both calendars.
See a health worker early
If you are pregnant, start antenatal care early, ideally in the first 12 weeks. In Nepal, the national guideline suggests 8 check-ups; see antenatal check-ups in Nepal.
Cycella Pregnancy, for adults, keeps your weeks, estimated due date, visits and questions on your phone. It is free on Google Play. See Cycella Pregnancy.
Sources
Try the Due date calculator, or see Cycella Pregnancy (free on Google Play). Cycella is a free, private Android period tracker, now on Google Play.
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