Due Date Calculator
Estimate a pregnancy due date and how far along you are.
Result
Estimated due dateExample
- How far along
- 8 weeks and 4 days (first trimester)
- Days until the due date
- 220 days
| Milestone | Week | Date |
|---|---|---|
| End of the first trimester | 13w 6d | Mon 7 Dec 2026 |
| Anatomy scan (usual week) | 20w 0d | Tue 19 Jan 2027 |
| Third trimester begins | 28w 0d | Tue 16 Mar 2027 |
| Early term begins | 37w 0d | Tue 18 May 2027 |
| Full term begins | 39w 0d | Tue 1 Jun 2027 |
| Due date | 40w 0d | Tue 8 Jun 2027 |
| Post-term from | 42w 0d | Tue 22 Jun 2027 |
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- Due date = first day of the last period + 280 days (Naegele’s rule)
About 4% of babies arrive on the due date; most come within two weeks. An early scan is more accurate.
General information, not medical advice.
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Questions
How is the due date worked out?
By Naegele’s rule: 280 days (40 weeks) after the first day of the last period, adjusted if your cycle is longer or shorter than 28 days. From conception it is 266 days.
How accurate is a due date?
It is an estimate. Only around 4% of babies are born on the date itself; most arrive within two weeks either side. An early ultrasound gives a more precise date.
Why is pregnancy counted from the last period?
Because that date is usually known while conception isn’t. So at conception a pregnancy is already counted as about 2 weeks along.
Is it free? Do I need an account?
It is free to use and there is nothing to sign up for. There are no watermarks and no daily limits.
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