Find your estimated due date, how far along you are today and the milestone dates. Runs on your device.
A due date is 280 days, or 40 weeks, after the first day of the last period, adjusted for cycle length. The page uses Naegele's rule: due date = first day of last period + 280 days + (cycle length − 28). For a last period starting on 10 January 2026 and a 28-day cycle, the due date is Saturday 17 October 2026. With a 32-day cycle it moves 4 days later to Wednesday 21 October 2026, and with a 24-day cycle 4 days earlier to Tuesday 13 October 2026. The cycle length can be 20 to 45 days. The count starts at the cycle-adjusted day, which the formula box shows as the pregnancy start.
Ovulation and conception come about 14 days after the first day of a 28-day cycle, so from a conception date the page adds 266 days. A conception date of 1 March 2026 gives Sunday 22 November 2026. For IVF the embryo's age is already known, so the page counts from the transfer date: add 263 days for a day-3 embryo and 261 days for a day-5 embryo. A transfer on 1 February 2026 gives Thursday 22 October 2026 for a day-3 embryo and Tuesday 20 October 2026 for a day-5 embryo. In every method the pregnancy start is the due date minus 280 days, and weeks are counted from that start.
The page takes today's date from your device and counts whole days from the pregnancy start. On 4 April 2026 a last period from 10 January 2026 is 84 days, shown as 12 weeks 0 days, which is the first trimester. The first trimester ends at 13 weeks 6 days, the second runs to 27 weeks 6 days, and the third starts at 28 weeks. The table gives a date for the end of the first trimester, an 18 to 22 week window commonly used for the mid-pregnancy anatomy scan, 24 weeks, 28 weeks, and the term labels from the American College of Obstetricians and Gynecologists (ACOG): early term from 37 weeks 0 days to 38 weeks 6 days, full term from 39 weeks 0 days to 40 weeks 6 days, late term from 41 weeks 0 days to 41 weeks 6 days, and post-term from 42 weeks 0 days. The table also lists the 40-week due date. For the example above, early term begins on 26 September 2026, full term on 10 October 2026, late term on 24 October 2026 and post-term on 31 October 2026.
The result is an estimate, not medical advice. A due date is a point in a range, and a dating scan, your midwife or your doctor may give a different date. The page accepts a first date from the last 44 weeks up to 4 weeks ahead and shows a message under the box for anything else. If you leave the date empty, it shows an example 8 weeks along, and says so in the note, so the page is not blank when you open it. Irregular cycles, an unknown last period and pregnancies after fertility treatment other than IVF transfer are not covered.
Add 280 days to the first day of your last period, then add or subtract the difference between your cycle length and 28. A period starting 10 January 2026 with a 28-day cycle gives Saturday 17 October 2026. The same date with a 32-day cycle gives Wednesday 21 October 2026.
Pick your method and enter the date. The page counts the days from the pregnancy start to today and shows them as weeks and days. For a last period on 10 January 2026, on 4 April 2026 that is 84 days, so 12 weeks 0 days.
Add 266 days to the conception date. A conception date of 1 March 2026 gives Sunday 22 November 2026. That is the same as adding 280 days to a last period 14 days before conception, so the milestone table uses the same week numbers.
Use the transfer date and the age of the embryo. Add 263 days for a day-3 embryo or 261 days for a day-5 embryo. For a transfer on 1 February 2026 that gives 22 October 2026 for day 3 and 20 October 2026 for day 5.
On this page the first trimester ends at 13 weeks 6 days, so the second starts at 14 weeks 0 days and runs to 27 weeks 6 days. The third trimester starts at 28 weeks. The table shows the date of each for your own due date.
No. The date stays in this tab and is not stored on your device or sent anywhere. Reloading the page puts the example back. The page only counts that a result was shown, without any of your dates.