Pregnancy Due Date Calculator
Work out your estimated due date and see how many weeks along you are, with the key milestones of each trimester mapped out.
28 days is the standard assumption
Estimated due date
Fri, 2 April 2027
How far along
8w 4d
First trimester
Days to go
220
Conception around Fri, 10 July 2026
| Milestone | Date |
|---|---|
| End of first trimester | Fri, 25 September 2026 |
| Anatomy scan (around 20 weeks) | Fri, 13 November 2026 |
| End of second trimester | Fri, 1 January 2027 |
| Full term begins (37 weeks) | Fri, 12 March 2027 |
| Estimated due date (40 weeks) | Fri, 2 April 2027 |
The due date is calculated by Naegele rule: 280 days from the first day of the last period, adjusted for cycle length. Only about 4% of babies arrive on the estimated date, and anything from 37 to 42 weeks is considered normal. An early dating scan is more accurate than any calculation. This is an estimate, not medical advice — your doctor or midwife should confirm the date.
Frequently Asked Questions
How is the due date calculated?
By Naegele rule: 280 days from the first day of your last period. This calculator also adjusts for cycle length, since a longer cycle means later ovulation and therefore a later due date.
How likely am I to deliver on the due date?
Only about 4% of babies arrive on their estimated date. Anything from 37 to 42 weeks is considered normal — the due date is the centre of a range, not a deadline.
Why does pregnancy count from the last period?
Because the date of the last period is something you can know, while the exact moment of conception usually is not. It means the first two weeks of the count happen before conception, which is why the 40 weeks is really about 38 weeks of gestation.
Is a dating scan more accurate?
Yes, especially between 8 and 13 weeks, when embryo size predicts gestational age within a few days. If a scan date differs from your calculated date by more than a week, doctors normally adopt the scan date.
Why is the IVF calculation different?
Because with IVF the conception date is known precisely. A day-5 blastocyst transfer means the due date is 261 days from transfer, which is far more accurate than working back from a period.