Pregnancy Due Date Calculator
Work out when your baby is due and how far along you are today. Calculate from the first day of your last period, the date of conception or an IVF transfer date.
Result
- You are
- 12 weeks, 0 days pregnant
- Trimester
- First trimester
- Pregnancy completed
- 30%
- Days until due date
- 196 days
- Estimated conception date
- August 25, 2026
- Gestational start (LMP)
- August 11, 2026
| Milestone | Week | Date | Status |
|---|---|---|---|
| End of first trimester | Week 13 | Mon, Nov 16, 2026 | in 13 days |
| Second trimester begins | Week 14 | Tue, Nov 17, 2026 | in 14 days |
| Halfway point | Week 20 | Tue, Dec 29, 2026 | in 56 days |
| Viability milestone | Week 24 | Tue, Jan 26, 2027 | in 84 days |
| Third trimester begins | Week 28 | Tue, Feb 23, 2027 | in 112 days |
| Early term | Week 37 | Tue, Apr 27, 2027 | in 175 days |
| Full term | Week 39 | Tue, May 11, 2027 | in 189 days |
| Due date | Week 40 | Tue, May 18, 2027 | in 196 days |
How the due date is calculated
A full-term pregnancy lasts about 40 weeks, or 280 days, counted from the first day of the last menstrual period (LMP). Conception usually happens around day 14 of the cycle, so the baby is actually about 38 weeks old at birth. The estimated due date (EDD) is the day the pregnancy reaches 40 weeks.
- Naegele's rule (from LMP): due date = LMP + 280 days. For cycles that are not 28 days, add or subtract the difference: a 35-day cycle moves the date 7 days later.
- From conception: due date = conception date + 266 days (38 weeks).
- From IVF transfer: due date = transfer date + 261 days for a day-5 embryo, or + 263 days for a day-3 embryo, following the American College of Obstetricians and Gynecologists guidance.
Worked example: if the last period started on August 1, adding 280 days gives a due date of May 8 the following year. On November 1, 92 days have passed, so the pregnancy is 13 weeks and 1 day along, at the end of the first trimester, with 188 days to go.
Trimesters and milestones
Pregnancy is divided into three trimesters. The first runs to the end of week 13, the second from week 14 to the end of week 27 and the third from week 28 to birth. Babies born from 37 weeks are "early term", 39 to 40 weeks is "full term" and 41 weeks is "late term". The milestone table lists these dates for your pregnancy and can help with planning scans, maternity leave and travel.
How to use this calculator
- Choose which date you know: last period, conception or embryo transfer.
- Enter the date. For the LMP method, adjust the cycle length if yours is consistently different from 28 days.
- Read your due date, how many weeks pregnant you are today and the key dates ahead. To count the days to any other date, try the date calculator.
Limitations
The calculation assumes ovulation on a fixed day of the cycle, which varies from person to person and month to month. A first-trimester ultrasound is the most accurate way to date a pregnancy, and your care provider may adjust the date based on it. This calculator is for information only and is not medical advice.
Frequently asked questions
How accurate is the due date?
Only about 4 to 5 percent of babies arrive on the estimated date; most are born within two weeks either side. The estimate is most reliable when it is confirmed by an ultrasound measurement in the first trimester, which is accurate to about 5 to 7 days.
Why does pregnancy count from the last period if I was not pregnant yet?
Doctors date pregnancy from the first day of the last menstrual period because it is a date most women know, while the exact day of ovulation and conception usually is not. By this convention you are "4 weeks pregnant" at the time of a missed period, even though conception happened about two weeks earlier.
What if my cycles are irregular?
Naegele's rule assumes ovulation on day 14 of a 28-day cycle. If your cycles are consistently longer or shorter, entering the cycle length shifts the estimate. For irregular cycles the LMP method is unreliable, and an early ultrasound is the best way to date the pregnancy.
Will my doctor change the due date later?
Possibly. If an early ultrasound differs from the LMP-based date by more than about 5 to 7 days, clinicians usually adopt the ultrasound date. Once set in the first trimester, the due date is normally not changed again, even if later scans suggest the baby is large or small.