🤰 Pregnancy Due Date Calculator
Estimate your baby’s due date, how far along you are and the key dates of your pregnancy.
Quick answer: Add 280 days (40 weeks) to the first day of your last period. If your last period started on June 1, 2026 with a 28-day cycle, your estimated due date is March 8, 2027.
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Pregnancy Due Date Calculator inputs
Result
Estimated due date
March 8, 2027
Only about 4% of babies arrive on the exact day – most come within ±2 weeks
- Pregnant today
- 18w 6d
- Trimester
- Second trimester
- Days to go
- 148 days
An estimate only – your provider may adjust it after an early ultrasound.
Pregnancy milestones
| Week | Date | Milestone |
|---|---|---|
| 6w | July 13, 2026 | Heartbeat usually visible on ultrasound |
| 8w | July 27, 2026 | First prenatal visit (typical) |
| 12w | August 24, 2026 | Dating / nuchal translucency scan (11–14 wks) |
| 14w | September 7, 2026 | Second trimester begins |
| 20w | October 19, 2026 | Anatomy scan (18–22 wks) |
| 24w | November 16, 2026 | Glucose screening window opens (24–28 wks) |
| 28w | December 14, 2026 | Third trimester begins |
| 37w | February 15, 2027 | Early term (37 wks) |
| 39w | March 1, 2027 | Full term (39 wks) |
| 40w | March 8, 2027 | Estimated due date |
| 42w | March 22, 2027 | Post-term (42 wks) |
How your due date is estimated
The standard method is Naegele’s rule: a pregnancy lasts on average 280 days (40 weeks) from the first day of the last menstrual period (LMP). This calculator adjusts for cycle length and supports conception and IVF dates too.
Due date = LMP + 280 days + (cycle length − 28)
Conception + 266 days · Day-3 transfer + 263 days · Day-5 transfer + 261 days
Worked example
Last period began June 1, 2026 with a 28-day cycle. Adding 280 days gives a due date of March 8, 2027. On October 11, 2026 that pregnancy is 132 days along – 18 weeks 6 days, in the second trimester. With a 32-day cycle the due date would move four days later, to March 12, 2027.
Trimesters at a glance
| Trimester | Weeks | Highlights |
|---|---|---|
| First | 0–13 | Organs form; dating scan around 11–14 weeks |
| Second | 14–27 | Anatomy scan around 20 weeks; movement felt |
| Third | 28–40+ | Rapid growth; full term from 39 weeks |
Good to know
- This is an estimate – your midwife or doctor may revise it after an ultrasound, which takes priority.
- If your cycles are irregular, the LMP method is less reliable; use a conception or scan date if you have one.
- “Weeks pregnant” is counted from the LMP, not from conception.
- This tool is not a form of contraception or a substitute for prenatal care.
Keep your appointments: early scans and checks matter far more than any date estimate.
For general information only – not medical advice. Consult a healthcare professional.
Frequently asked questions
How accurate is a due date?
It is an estimate. Only around 4–5% of babies are born on their due date; most arrive between 38 and 42 weeks. A first-trimester ultrasound is the most accurate way to date a pregnancy.
Why is pregnancy counted from the last period?
The date of the last period is usually known, while ovulation and conception are not. Counting from it adds about two weeks before conception, so a “40-week” pregnancy is roughly 38 weeks from conception.
How does cycle length change the due date?
Naegele’s rule assumes a 28-day cycle with ovulation on day 14. Longer cycles mean later ovulation, so each extra day pushes the due date back a day; shorter cycles bring it forward.
How is an IVF due date calculated?
IVF dates are precise: add 263 days to a day-3 embryo transfer or 261 days to a day-5 (blastocyst) transfer.