Estimate your baby's due date from five different starting points.
Conceived on 29 January 2026? Add 266 days for a due date of Thursday, 22 October 2026. From your last period, add 280 days; from a 3-day IVF transfer, 263 days; from a 5-day transfer, 261 days.
Your estimated due date (EDD) depends on how your pregnancy is dated. This calculator supports the last menstrual period, a known conception date, a 3-day or 5-day IVF embryo transfer and an ultrasound measurement, and shows the delivery window (37 to 42 weeks), full-term dates and trimester dates.
An early ultrasound is the most accurate way to date a pregnancy, and your doctor may change your due date after the first scan. For progress, weeks pregnant and a week-by-week calendar try the Pregnancy Calculator; to work backwards, use the Pregnancy Conception Calculator.
The calculator applies the standard published formulas step by step.
| Item | Value |
|---|---|
| Estimated due date | Thursday, 22 October 2026 |
| Pregnancy progress | 12 weeks 6 days (week 13) |
| Days until the due date | 190 |
| Estimated first day of last period | Thursday, 15 January 2026 |
| Estimated date of conception | Thursday, 29 January 2026 |
| First trimester | Thursday, 15 January 2026 – Wednesday, 22 April 2026 |
| Second trimester | Thursday, 23 April 2026 – Wednesday, 29 July 2026 |
| Third trimester | Thursday, 30 July 2026 – Thursday, 22 October 2026 |
| Full-term window (39–40 weeks 6 days) | Thursday, 15 October 2026 – Wednesday, 28 October 2026 |
| Delivery window (37–42 weeks) | Thursday, 1 October 2026 – Thursday, 5 November 2026 |
| Week | Date it starts | What happens |
|---|---|---|
| Week 4 | Thursday, 12 February 2026 | Missed period — a home pregnancy test can show positive |
| Week 8 | Thursday, 12 March 2026 | Early dating ultrasound is often done around now (6–9 weeks) |
| Week 12 | Thursday, 9 April 2026 | Many people share the news; the first-trimester screening scan is at 11–13 weeks + 6 days |
| Week 14 | Thursday, 23 April 2026 | Second trimester begins |
| Week 20 | Thursday, 4 June 2026 | Anatomy (anomaly) scan, usually between 18 and 22 weeks |
| Week 24 | Thursday, 2 July 2026 | Glucose screening is commonly offered between 24 and 28 weeks |
| Week 28 | Thursday, 30 July 2026 | Third trimester begins |
| Week 36 | Thursday, 24 September 2026 | Baby is usually head-down; weekly checks may start |
| Week 37 | Thursday, 1 October 2026 | Early term begins (full term from 39 weeks) |
| Week 40 | Thursday, 22 October 2026 | Estimated due date |
| Week 42 | Thursday, 5 November 2026 | Post-term — doctors usually plan induction before this |
| Case | Due date |
|---|---|
| Conceived 29 Dec 2025 | Monday, 21 September 2026 |
| Conceived 29 Jan 2026 | Thursday, 22 October 2026 |
| Conceived 28 Feb 2026 | Saturday, 21 November 2026 |
| 5-day transfer 3 Feb 2026 | Thursday, 22 October 2026 |
| 3-day transfer 1 Feb 2026 | Thursday, 22 October 2026 |
Add 280 days to the first day of your last period, or 266 days to the conception date.
Add 261 days to the date of a day-5 embryo transfer or 263 days to a day-3 transfer (equivalent to 266 days after fertilisation).
Yes. If the scan differs from your LMP date by more than about 5–7 days in the first trimester, doctors usually use the scan date.
Only about 4–5%. Most arrive within two weeks either side.
39 weeks. Babies born at 37–38 weeks are early term.
Yes. A cycle longer than 28 days means later ovulation, so the due date moves later by the same number of days.
It uses the published formula: EDD = LMP + 280 days = conception + 266 days = 5-day transfer + 261 days The full method and a worked example are shown on this page.
No. The calculator gives general estimates for information and education. It cannot diagnose or treat anything, so please speak to a doctor or qualified professional about your own health.
Yes. Choose centimetres or feet and inches for height, and kilograms, pounds or stone for weight; the results are converted for you.
No. Everything is calculated in your browser and nothing you enter is uploaded or saved.
